This is an appeal taken from a judgment of sentence imposed following a jury trial at which appellant was convicted of aggravated assault,1 resisting arrest2 and conspiracy3. After post-trial motions were denied appellant was sentenced to concurrent five-year terms of probation for aggravated assault and conspiracy. Sentence for resisting arrest was suspended. This appeal followed.
Appellant’s convictions arose from events which occurred during the early morning hours in the Frankford section of Philadelphia. Police officer John Welsh was summoned to the scene of a fight. When he arrived he saw appellant Kathleen French and three companions assaulting a lone *439black man who was pinned to the ground and being beaten by his four assailants. Appellant’s companions were James Moran, appellant’s boyfriend, Elizabeth Quinn, appellant’s sister and Michael Haughey, the sister’s boyfriend.
Officer Welsh pushed appellant, Quinn and Moran back from their victim and then pulled Haughey off him. Meanwhile, three more police officers were arriving at the scene: Officers Stephan, Draft and Griffin. After the parties were separated, the police asked the man with whom appellant and her friends had been fighting whether he wanted to press charges. He stated that he did not, at which point the police told him to leave. Although the police also instructed appellant and her companions to leave, they did not comply. Instead, appellant, Moran, Quinn and Haughey began shouting obscenities and insults at the police officers.4 More than once the police asked the group to leave. Co-defendant Michael Haughey then made an offensive remark to Officer Welsh and punched him in the face. Welsh struck Haughey in response and then attempted to place him under arrest.
While Welsh was trying to control Haughey, co-defendant James Moran also struck Welsh in the face with his fist. Officers Welsh and Stephan attempted to handcuff Haughey while Officers Griffin and Draft struggled to do the same with Moran. First Haughey was placed under arrest and Officer Stephan was able to come to the aid of the officers who were grappling with Moran. Finally, with three officers involved in the effort, Moran was handcuffed. During the effort to subdue Moran and Haughey, appellant and her sister were circling the officers, continuing to hurl verbal abuse at the police. At one point, appellant also ran up to Officer Welsh and punched him “square in the nose”. Officer Stephan grabbed appellant and, despite her resistance, arrested and handcuffed her. Appellant and Moran, in particular, continued to struggle and shout obscenities at *440the officers during the ride to the police station. When they arrived Moran resisted the officers’ attempts to remove him from the police van and place him in a cell.
On appeal, appellant makes several claims of error concerning the conduct of her trial.5 She contends that: 1) the evidence was insufficient to sustain a conviction for conspiracy; 2) the trial court erroneously instructed the jury on various matters, in particular, on the definition of the defense of justification; 3) the trial court improperly restricted cross-examination of police witnesses regarding an Internal Affairs Investigation of the above-described incident; and 4) after conducting an in camera inspection, the trial court erred in refusing to turn over to defense counsel certain statements which the police witnesses had given to the Internal Affairs investigators.
—Criminal Conspiracy—
The applicable standard of review for challenges to the sufficiency of evidence is well-settled. We must determine whether, viewing all the evidence at trial, as well as all reasonable inferences to be drawn therefrom, in the light most favorable to the Commonwealth, the jury could have found that each element of the offense was proven beyond a reasonable doubt. Both direct and circumstantial evidence can be considered equally when assessing the sufficiency of the evidence. Commonwealth v. Hughes, 521 Pa. 423, 429-31, 555 A.2d 1264, 1267 (1989); Commonwealth v. Ogin, 373 Pa.Super. 116, 540 A.2d 549 (1988) (en banc).
Appellant contends that the evidence of conspiracy fails to satisfy this standard because the Commonwealth failed to establish a conspiratorial agreement among the parties. It is clear that essential to the crime of conspiracy is a common understanding and agreement that a crime will be committed. See Commonwealth v. Derr, 501 Pa. 446, 462 A.2d 208 (1983); Commonwealth v. Anderson, 381 Pa.Super. 1, 552 A.2d 1064 (1988). It is equally plain that *441direct proof of such an agreement is rarely available, nor is it necessary. Thus, “proof of a criminal partnership is almost invariably extracted from the circumstances that attend its activities”. Commonwealth v. Campbell, 353 Pa.Super. 178, 180-81, 509 A.2d 394, 395 (1986) (quoting Commonwealth v. Strantz, 328 Pa. 33, 43, 195 A. 75, 80 (1937)). An agreement can be inferred from a variety of circumstances including, but not limited to, the relation between the parties, knowledge of and participation in the crime, and the circumstances and conduct of the parties surrounding the criminal episode. These factors may coalesce to establish a conspiratorial agreement beyond a reasonable doubt where one factor alone might fail. See Commonwealth v. Lamb, 309 Pa.Super. 415, 429, 455 A.2d 678, 685-86 (1983).
Appellant argues that the Commonwealth’s evidence proved only a spontaneous, impulsive confrontation between appellant, her cohorts and the police, and the evidence therefore was insufficient to show conspiracy. She relies on Commonwealth v. Kennedy, 499 Pa. 389, 453 A.2d 927 (1982). However, Kennedy is distinguishable. In Kennedy, the Supreme Court found insufficient evidence of a conspiracy where the defendant and his alleged co-conspirator assaulted the landlord of the building in which defendant lived. The court found nothing in the relationship of the parties to indicate an implicit or explicit agreement to engage in an assault and found that although the parties acted simultaneously, they nevertheless acted independently-
Here, on the other hand, all the co-conspirators acted as a group in concert. Before the police arrived, they acted together to commit an assault on the lone black man. They were told as a group to disperse but instead they decided, as a group, to stay and engage in joint criminal conduct in which each was spurring the others on toward a common criminal purpose. It is unnecessary to prove an explicit and formal agreement between the conspirators. The agreement necessary to support a conspiracy conviction can be *442wholly tacit so long as the surrounding circumstances confirm that the parties have decided to act in concert. In this case, the actors’ relationships and their conduct before, during and after the criminal episode established a unity of criminal purpose sufficient for the jury to find conspiracy beyond a reasonable doubt.
—Jury Instructions—
Appellant makes three claims with respect to the trial court’s instructions to the jury. First she argues that the trial court confused the jury by erroneously omitting which police officer was the “object” of the conspiracy. Next she claims that the trial court erred by failing to give the jury her suggested charge on prior inconsistent statements. Her third complaint with respect to the trial court’s charge is that the court incorrectly stated the law on “justification” by erecting a more onerous standard than the Crimes Code dictates. Specifically, she argues that she was entitled to a charge on justification which would have informed the jury that she was justified in using force against a police officer if she reasonably believed he threatened any bodily injury to a third party (in this case James Moran). In its instructions the trial court restricted the justification defense to those instances where serious bodily injury or death is threatened.
We may quickly dispose of appellant’s first two arguments regarding conspiracy and prior inconsistent statements. It is axiomatic that in evaluating jury instructions we review the charge as a whole, not as isolated excerpts. Reversal is required only if the asserted errors resulted in prejudice to the defendant. See Commonwealth v. Riggins, 374 Pa.Super. 243, 253, 542 A.2d 1004, 1009 (1988). In the instant case, the trial court indicated to the jury that only police officer Welsh was the intended victim of appellant’s actions. Thus appellant’s assertion that the court failed to identify the officer who was the victim of the conspiracy is wholly without merit.
Additionally, the trial court did not err in refusing to instruct the jury on appellant’s requested instruction on *443prior inconsistent statements. A review of the record reveals that the trial court’s instructions adequately and clearly presented the law to the jury. The judge was not required to accept requested instructions. See Commonwealth v. Cimorose, 330 Pa.Super. 1, 478 A.2d 1318 (1984).
Lastly, we address appellant’s argument that the trial court’s instruction on the justification defense was in error. The issue appears to be one of first impression in this Commonwealth. After carefully examining decisions from other jurisdictions and evaluating the underlying policy implications, we conclude that the trial court correctly instructed the jury on the necessary components of a justification defense in the context of resisting arrest.
At trial appellant testified that she struck Officer Welsh in an effort to stop him from injuring her boyfriend, James Moran. She claimed that the police officers were beating Moran about the head and body with nightsticks and that at one point one officer had his foot on Moran’s throat, choking him. Because “they wouldn’t stop beating him”, appellant went to Moran’s aid by hitting the police officer. The trial court charged the jury on the law of the defense of justification as follows:
Now, in this case justification is a defense, if the defendant French reasonably believed that her intervention was necessary to protect Moran from death or serious bodily injury and that the force used was immediately necessary to protect Moran against the force used by Officer Welsh on the same occasion as Miss French used force.
Because the Commonwealth has the burden of disproving the defense of justification, you may find Miss French guilty only if you are satisfied beyond a reasonable doubt either that French did not reasonably believe that her intervention was necessary to protect Moran or that she did not reasonably believe that the force she used was immediately necessary to protect Moran then and there against the force used by Officer Welsh. (Emphasis added).
*444Appellant argues that the trial court’s instruction was incorrect in that it limited her justification defense to those situations wherein the arresting officer’s use of excessive force threatens serious bodily injury or death. She asserts that a citizen should prevail on a justification claim where the force exerted by the police is excessive only to the extent that any bodily injury is threatened.
The general principle that an individual may not use force to resist even an unlawful arrest made by a known police officer is not challenged by the appellant. Rather we are asked to decide whether force under some circumstances is justifiable, and if we conclude that force is justifiable, what are those circumstances.6
The defense of justification is covered generally in our Crimes Code in Sections 501 through 510. In particular, section 505 provides:
(a) Use of force justifiable for the protection of the person. The use of force upon or toward another person is justifiable when the actor believes that such force is immediately necessary for the purpose of protecting himself against the use of unlawful force by such other person on the present occasion.
(b) Limitations on justifying necessity for use of force.—
(1) The use of force is not justifiable under this section:
(i) to resist an arrest which the actor knows is being made by a peace officer, although the arrest is unlawful;
18 Pa.Cons.Stat.Ann. § 505(a) and (b)(1)(i) (Purdon 1983).
Section 506 further provides that a person is justified in using force to protect a third person under the same circum*445stances and to the same extent as he or she would be justified under the rules of self-protection.7
Our statutory scheme, which prohibits the use of force in resisting even an illegal arrest by one known to be a law enforcement officer, reflects the modern trend to abrogate the traditional but outdated common law rule. The established rule had been that a person had the right to use force to resist an illegal arrest. Either by statute or by case law, many jurisdictions have moved toward a more enlightened view, i.e., disputes about the legality of an arrest are more properly settled in court than in the potentially explosive atmosphere of the street.8 Thus, based on statute and sound reasoning, the courts of Pennsylvania have consistently held that “even an unlawful arrest does not excuse an assault upon an arresting police officer”. Commonwealth v. McKeirnan, 337 Pa.Super. 403, 408, 487 A.2d 7, 10 (1985); Commonwealth v. Meoli, 307 Pa.Super. 50, 452 A.2d 1032 (1982); Commonwealth v. Temple, 258 Pa.Super. 269, 392 A.2d 788 (1978); Commonwealth v. Whitner, 241 Pa.Super. 316, 361 A.2d 414 (1976) (en banc).
In the instant case the Commonwealth urges us to end our inquiry here. However to do so would be to avoid the legitimate and important issue appellant has raised as to whether the use of excessive force by the police officer in effectuating an arrest allows the arrestee to invoke the right of self-defense and, more critical to the disposition of this case, what amount of force by the police is necessary to overcome a citizen’s duty to submit peacefully to arrest.
*446A surface reading of the applicable statutes would suggest that they eliminate altogether the justification defense for those persons using force to resist an arrest by a police officer even if the arrest is unlawful. However, thoughtful analysis compels the conclusion that situations exist where justification may be an appropriate defense. The Official Comment to Title 18, section 505 supports this view and provides: “Under Subsection (b)(1)(i) the actor may use force if the arresting officer unlawfully uses or threatens deadly force.” 18 Pa.Cons.Stat.Ann. § 505 (Purdon Supp.1989) (emphasis added). Moreover the Official Comment notes that the justification section in our Crimes Code is derived from section 3.04 of the Model Penal Code of the American Law Institute. Section 3.04 of the Model Penal Code also provides that a justification defense is denied for the use of force in resisting even an unlawful arrest made by a known police officer. In limiting this principle, however, the Model Penal Code Comment notes:
[I]t has no application when the actor apprehends bodily injury, as when the arresting officer unlawfully employs or threatens deadly force, unless the actor knows that he is in no greater peril than arrest if he submits to the assertion of authority. The actor thus does not lose his justification if the officer uses more force than is necessary to effect the arrest, or otherwise constitutes a danger to the safety of the citizen.
Model Penal Code § 3.04, Comment at 43 (emphasis added).
Thus it is clear that in enacting section 505(b)(1)(i), which in general deprives a person of authority forcibly to resist an unlawful arrest, the legislature did not intend the section to apply to a situation in which an officer uses excessive force. Additional authority for this conclusion comes from Toll’s Annotations to the Pennsylvania Crimes Code in which Toll quotes the above underscored comment from the Model Penal Code with approval in explaining the application of section 505(b)(1)(i).
Furthermore, logic compels the same conclusion. As the Supreme Court of New Jersey cogently articulated:
*447There is sound reason for a difference in the rights and duties of the citizen in the two situations [an illegal arrest accomplished without excessive force versus one where excessive force is employed]. Despite his duty to submit quietly without physical resistance to an arrest made by an officer acting in the course of his duty, even though the arrest is illegal, his right to freedom from unreasonable seizure and confinement can be protected, restored and vindicated through the legal processes. However, the rule permitting reasonable resistance to excessive force of the officer, whether the arrest is lawful or unlawful, is designed to protect a person’s bodily integrity and health and so permits resort to self-defense. Simply stated, the law recognizes that liberty can be restored through legal processes but life or limb cannot be repaired in a courtroom. And so it holds that the reason for outlawing resistance to an unlawful arrest and requiring disputes over its legality to be resolved in the courts has no controlling application on the right to resist an officer’s excessive force.
State v. Mulvihill, 57 N.J. 151, 156-57, 270 A.2d 277, 280 (1970) (citation omitted) (emphasis added).
Relying on this or similar reasoning the majority of jurisdictions justify an arrestee’s use of self-defense when an arrest is being effectuated by the use of excessive force.9 Often this rule is stated in the negative, that is, that in the absence of excessive force by an arresting officer, a citizen may not use force to resist arrest, whether or not the arrest is illegal under the circumstances. Unfortunately, while we concur in this general proposition, it does not complete the crucial inquiry here. We must decide what *448degree of force by the police triggers the right forcefully to resort to self-defense.
We hold that an arrestee may resist excessive force by a known police officer only if serious bodily injury or death is threatened or inflicted. We are persuaded of the correctness of this holding for two reasons.
First, we believe that the violent potential of the arrest context dictates that a more limited and stringent application of self-defense principles is demanded. Force is justified only in the face of a threat of serious bodily injury or death. To sanction a lesser standard would encourage unnecessary violence and invite the kind of escalating retaliatory conduct which this case dramatically demonstrates. Arrests often take place on the street or in other crowded, hostile environments. To allow an arrestee or a bystander to intensify the danger by forcefully resisting an overly aggressive arrest when any bodily injury is feared would not serve the interests of peace in society. We stress that our conclusion in no way condones excessively assaultive police conduct.
We find persuasive the language of the Court of Appeals of the State of Washington:
We emphatically do not countenance a use of force by police which exceeds that essential to effect an arrest, but the arrestee’s right to freedom from arrest without excessive force that falls short of causing serious injury or death can be protected and vindicated through legal processes, whereas loss of life or serious physical injury cannot be repaired in the courtroom. However, in the vast majority of cases, as illustrated by the one at bar, resistance and intervention make matters worse, not better. They create violence where none would have otherwise existed or encourage further violence, resulting in a situation of arrest by combat. Police today are sometimes required to use lethal weapons for self protection. If there is resistance on behalf of the person lawfully arrested and others go to his aid, the situation can degenerate to the point that what should have been a simple *449lawful arrest leads to serious injury or death to the arrestee, the police or innocent bystanders. Orderly and safe law enforcement demands that an arrestee not resist a lawful arrest and a bystander not intervene on his behalf unless the arrestee is actually about to be seriously injured or killed.
State v. Westlund, 13 Wash.App. 460, 467, 536 P.2d 20, 25 (1975).10
The court in Westlund went one step further than this court is prepared to go in limiting the use of self-defense in the arrest context. The Washington courts would countenance resistance by an arrestee only if he was actually about to be seriously injured or killed. We conclude that where a person reasonably believes himself to be in genuine danger of death or serious bodily injury, he may defend himself against that injury by the use of reasonable force. We think that this formulation protects the competing interests implicated here. The jury, when accurately instructed, must resolve the factual issues regarding the reasonableness of the arrestee’s apprehension of the degree of excessive force allegedly being used against him.
Finally, we rely for support for our holding on the language of the commentary to our Crimes Code and to the Model Penal Code from which it is derived. We believe that this language, i.e., that an actor may invoke the justification defense “when the actor apprehends bodily injury, as when the arresting officer unlawfully employs or threatens deadly force ” was intended to illustrate the gravity of the situations wherein the defense could legitimately be asserted. We do not agree that any bodily injury would rise to the level of the deadly force illustration chosen by the commentators.
Here the trial court’s instruction was consistent with *450the law as we have outlined it.11 A third party (here appellant French) is entitled to come forcefully to the aid of a person being placed under arrest by a known police officer only if the officer was employing or threatening excessive force which she reasonably believed subjected the arrestee to serious bodily injury or death. The trial court so instructed the jury.
Internal Affairs Division Investigation
Appellant’s next two arguments concern the trial court’s actions regarding a previously completed Internal Affairs Division (IAD) inquiry into the episode from which these charges arose. Specifically, appellant argues that the trial court erred in refusing to allow defense counsel to cross-examine police witnesses regarding statements they may have given to the IAD investigators. Second, appellant argues that the trial court committed reversible error by refusing to turn over the officers’ statements made during the IAD investigation to defense counsel. She claims it was error for the court to rely on its own in camera inspection to assess whether the IAD statements were discoverable.
With respect to the first issue, we conclude that the trial court properly exercised discretion in the area of cross-examination. However, because the court should have permitted the defense to inspect statements in the IAD file, we remand for an evidentiary hearing before the trial court to determine whether the court’s failure to permit defense counsel personally to inspect the statements was harmless error.
The statements in question were made during the police department’s IAD inquiry which was triggered by a complaint filed by James Moran two days after his arrest. Moran’s complaint alleged that he was struck with nightsticks and suffered other physical abuse at the hands of the *451officers. Pursuant to the investigation the IAD took statements from all participants in the melee. At the conclusion of the investigation, IAD found Moran’s complaints to be unsubstantiated and resolved the matter in favor of the accused officers. The IAD inquiry was concluded and closed almost a year before appellant’s trial began. At trial appellant’s attorney attempted to cross-examine Officer Stephan regarding any statements he may have given to “anyone else” about the incident at issue. The Commonwealth objected and at a sidebar conference the fact of the IAD investigation was presented to the trial court. Rather than rule in a vacuum, the trial court ordered the IAD file turned over to the court for an in camera inspection to decide the propriety of using the officers’ statements for cross-examination. The following day, having conducted an in camera reading of the IAD file, the trial court concluded that no exculpatory material was contained therein nor were any of the officers’ statements inconsistent with trial testimony thus far elicited. At this point appellant’s counsel informed the court that not only did he want to review the IAD files for possible “Brady” material12 and inconsistent statements but, in addition, he wanted to use the existence of the IAD inquiry to argue that the officers’ trial testimony was somehow biased or embellished “because of the possibility of sanctions from the Police Department”. The Commonwealth objected, noting that the investigation was not instigated by the police but by a complaint from Moran and was long ago concluded, thereby negating any possible inference that these officers were “under investigation” and would be motivated to lie. The trial court refused to allow inquiry based on the IAD statements and refused to turn them over to the defense.
Appellant claims that the trial court’s action denied her the constitutionality guaranteed right to confront *452her witnesses in that it precluded her from arguing that the officers had possible motives to lie during the instant prosecution based upon their interests in the outcome of the IAD investigation. While it is true that potential bias and motivation to fabricate are properly the subject of cross-examination,13 it is also true that the scope of cross-examination lies within the sound discretion of the court and, absent palpable error, the trial court’s decision will not be reversed. Commonwealth v. Rivers, 383 Pa.Super. 409, 416, 557 A.2d 5, 9 (1989); Commonwealth v. Ross, 345 Pa.Super. 571, 498 A.2d 972 (1985). Here the trial court correctly concluded that the completed IAD investigation which exonerated the officers could not be probative of bias or motive to testify falsely and therefore properly disallowed cross-examination.
A brief comparison of the instant case to those upon which appellant principally relies illustrates why we are unpersuaded by her argument. In Commonwealth v. Sullivan, 485 Pa. 392, 402 A.2d 1019 (1979), the Supreme Court granted a new trial on the basis of improperly restricted cross-examination. In Sullivan the defendant was tried for assaulting a police officer who was arresting the defendant’s son. Through cross-examination, defense counsel in Sullivan tried to discredit the police officer’s testimony by demonstrating that following the incident at issue, the officer had been suspended from the police force and that the suspension was to continue pending the outcome of defendant’s case. The trial court refused to allow the cross-examination and the Supreme Court reversed. The witness’ interest in the outcome of the case in Sullivan was patent and the Supreme Court held that the defendant had the right to develop this theory through cross-examination.
In Commonwealth v. Dawson, 486 Pa. 321, 405 A.2d 1230 (1979), the defendant sought to cross-examine the homicide detective who had taken the defendant’s confession after arrest. The defendant in Dawson wanted to present to the jury the theory that the detective was moti*453vated to fabricate his confession in order to account for time spent allegedly beating another prisoner. Defendant sought to prove that the detective had been subjected to disciplinary action as a result of the beating. The Supreme Court held that defendant should have been entitled to develop this theory because the detective’s reputed misconduct and disciplining could have provided a basis for fabricating the confession.
Surely the instant case is not analogous. Here the IAD investigation was completed more than a year before appellant’s trial began. The officers involved were exonerated of wrongdoing and were not subject to disciplinary action of any kind. The IAD inquiry resulted in no past penalty for which the officers might theoretically seek vindication, nor were future sanctions even suggested. Appellant’s contention that the officers’ testimony “may have been motivated by a desire to avoid internal departmental sanctions, if not civil liability for their conduct”14 is pure speculation which has no support in the record.
Appellant also contends that the trial court erred by refusing to turn the IAD file over to defense counsel so that defense counsel independently could assess the potential impeachment value of the police officers’ statements. She asserts that the trial court’s failure to disclose the statements to her attorney deprived her of her right to confrontation as secured by the United States and Pennsylvania Constitutions. The gravamen of her argument is that the trial court is not in the role of an advocate, and is therefore incapable of determining the “discoverability” of the requested materials. She asserts that the trial court must disclose such materials to the defense despite the court’s informed judgment that the statements are devoid of impeachment value.
We conclude that because the officers were witnesses at the trial, the court’s denial of defense access to the police *454witnesses’ IAD statements constituted error. It is settled that where the Commonwealth has in its possession pretrial statements of its witnesses which have been reduced to writing and which relate to the witness’ testimony at trial, it must, upon request, furnish copies of the statements to defense. See e.g. Commonwealth v. Brinkley, 505 Pa. 442, 480 A.2d 980 (1984); Commonwealth v. Hassine, 340 Pa.Super. 318, 490 A.2d 438 (1986), appeal denied (1986); Commonwealth v. Kysor, 334 Pa.Super. 89, 482 A.2d 1095 (1984). This conclusion does not extend to the defense request for wholesale inspection of the entire IAD file. The Brinkley line of cases requires disclosure of witnesses’ statements and we decline to enlarge the rule to create a general rule of access to all of the Commonwealth’s files. Our analysis does not end with a finding of error, however. The Commonwealth argues that even if the trial court erred in denying access to the statements at issue, any such denial was harmless beyond a reasonable doubt because the statements were wholly consistent with the trial testimony given by the prosecution witnesses. While we agree with the Commonwealth that the error found here is properly subject to a harmlessness analysis, we find that both the interests of justice and relevant case law require us to allow defense counsel an opportunity to argue the merits of this issue to the trial judge who presided over the case.
Both the United States Supreme Court and the courts of this Commonwealth have long recognized the principle that “an otherwise valid conviction should not be set aside if the reviewing court may confidently say, on the whole record, that the constitutional error was harmless beyond a reasonable doubt”. Delaware v. Van Arsdall, 475 U.S. 673, 681, 106 S.Ct. 1431, 1436, 89 L.Ed.2d 674 (1986); Commonwealth v. Story, 476 Pa. 391, 383 A.2d 155 (1978); Commonwealth v. McGrogan, 367 Pa.Super. 394, 532 A.2d 1203, affirmed, 523 Pa. 614, 568 A.2d 924 (1990); see also Commonwealth v. Floyd, 508 Pa. 393, 498 A.2d 816 (1985); Commonwealth v. Howard, 375 Pa.Super. 43, 48-50, 543 A.2d 1169, 1172 (1988), appeal denied, 522 Pa. 573, 559 *455A.2d 35 (1989). This principle reflects a fundamental concept, i.e., “that the central purpose of a criminal trial is to decide the factual question of the defendant’s guilt or innocence, and promotes public respect for the criminal process by focusing on the underlying fairness of the trial rather than on the virtually inevitable presence of immaterial error.” Van Arsdall, 475 U.S. at 681, 106 S.Ct. at 1436 (citations omitted). If we conclude that the error complained of did not contribute to the verdict, no new trial is required.
Here, however, because defense counsel was never given access to the statements due an erroneous ruling by the trial court, the defense has not had an opportunity to argue to the appellate court the potential impact the excluded statements may have had on the verdict. In the instant case, the IAD statements were sought by defense counsel to ascertain whether the prior statements were inconsistent with trial testimony and might therefore provide a basis upon which to impeach the credibility of the police officers’ testimony. Without granting defense access to the witnesses’ pre-trial statements, the trial court assessed the disputed file and found the statements to be without impeachment value and of no use to the defense. This conclusion was reached without benefit of an advocate’s eye. Given the nature of our adversarial system of justice, this procedure has been condemned. Hence, in Commonwealth v. Hamm, 474 Pa. 487, 498-99, 378 A.2d 1219, 1225 (1977) the Supreme Court noted:
We recognize that the trial court has the ultimate responsibility to determine whether the prior statements may be used in cross-examining the witness or are otherwise admissible. However, like other evidentiary rulings, these determinations are properly made in an adversary context. We do not believe that the trial court can determine the value that the prior statements may have to the defense without hearing defense argument after inspection.
*456We are guided in our disposition of this case by this court’s decision in Commonwealth v. Meo, 362 Pa.Super. 328, 524 A.2d 902 (1987). In Meo this court had to determine whether the appellant was entitled to a new trial based on the failure of the trial court to disclose to defense counsel a police report prepared by an officer who testified at appellant’s trial. There we held that the trial court had indeed erred. In Meo the Commonwealth argued that the error was harmless because the report contained only cumulative evidence. While this court acknowledged that the “failure to grant a defense request for police reports may indeed be harmless error”, we noted the impossibility of making such a determination on a record which did not contain the disputed report.
Therefore we remanded to the trial court for an evidentiary hearing on the harmlessness issue. Commonwealth v. Meo, 362 Pa.Super. at 334-36, 524 A.2d at 905-06. Similarly, although in the instant case this court has the benefit of both the trial testimony and the IAD file, the impact of the trial court’s ruling on the jury’s verdict can only be fairly assessed once counsel has been given access to the witnesses’ statements and has advocated the defense position to the trial judge.15
We remand to the trial court for an evidentiary hearing on whether the court’s failure to allow defense access to the Commonwealth witnesses’ statements constituted harmless error. We reiterate that our holding does not extend to wholesale access to the IAD file but only to the pre-trial statements given by witnesses who testified at appellant’s trial. The standard by which the trial court must judge the harmlessness of the error here was recently reaffirmed by the Supreme Court in Commonwealth v. *457McGrogan, 523 Pa. 614, 568 A.2d 924 (1980). An error is harmless where the properly admitted evidence is so overwhelming and where the prejudicial impact of the error is so slight that it can be concluded beyond a reasonable doubt that the error could not have contributed to the jury’s verdict. McGrogan, 523 Pa. at 625-27, 568 A.2d at 930.
Here, if the trial court determines that the error was harmless, the judgment of sentence is affirmed. If the trial court finds that the error was not harmless, we direct the judgment of sentence to be vacated and appellant granted a new trial.
Case remanded for proceedings consistent with this opinion. Jurisdiction is relinquished.
WIEAND, J., files a concurring and dissenting opinion.. 18 Pa.Cons.Stat.Ann. § 2702 (Purdon 1983).
. 18 Pa.Cons.Stat.Ann. § 5104 (Purdon 1983).
. 18 Pa.Cons.Stat.Ann. § 903 (Purdon 1983).
. Appellant and the others were shouting epithets such as “nigger lover”, “mother f—ing nigger lover” and several other words in that manner.
. Appellant was tried jointly with Haughey and Moran. Quinn was charged with disorderly conduct only and was not tried with her companions.
. We are aware that the specific factual scenario presented in the instant case does not involve self-defense but rather intervention on behalf of a third party. In general, however, our justification statute places an intervenor in the shoes of the person whom he or she is aiding. 18 Pa.Cons.Stat.Ann. § 506 (Purdon 1983). Therefore, in this case, appellant French would be justified in using whatever force to prevent injury to Moran as Moran could use in self-defense. To simplify our discussion, we eliminate continual references to the third party situation.
. 18 Pa.Cons.Stat.Ann. § 506(a)(1) (Purdon 1983).
. See, e.g. Annotation, Modern Status of Rules as to Ribht to Forcefully Resist Illegal Arrest, 44 A.L.R.3d 1078 (1972); Chevigny, The Right to Resist an Unlawful Arrest, 78 Yale L.J. 1128 (1969); Note, Justification, Excuse, and Resisting Unlawful Arrest, 33 Wayne L.Rev. 1471, Summer, 1987.
As one court aptly noted:
“The legality of an arrest may often be a close question as to which even lawyers and judges may disagree. Such a close question is more properly decided by a detached magistrate rather than by the participants in what may well be a highly volatile imbroglio.” Commonwealth v. Moreira, 388 Mass. 596, 600, 447 N.E.2d 1224, 1227 (1983).
. See Annotation, The Right to Resist Excessive Force used in Accomplishing Lawful Arrest, 77 A.L.R.3d 281 (1977); see also Commonwealth v. Moreira, 388 Mass. 596, 447 N.E.2d 1224 (1983); People v. Bailey, 108 Ill.App.3d 392, 64 Ill.Dec. 75, 439 N.E.2d 4 (1982); Ivester v. State, 398 So.2d 926 (Fla.App. 1 1981); State v. Celinas, 417 A.2d 1381 (R.I.1980); State v. Mulvihill, 57 N.J. 151, 270 A.2d 277 (1970); Gray v. State, 463 P.2d 897 (Alaska 1970); People v. Curtis, 70 Cal.2d 347, 74 Cal.Rptr. 713, 450 P.2d 33 (1969).
. The Westlund holding was adopted and this language cited with approval in an en banc decision of the Washington Supreme Court. State v. Holeman, 103 Wash.2d 426, 693 P.2d 89 (1985) (en banc).
. In People v. Kelley, 3 Cal.App.3d 146, 83 Cal.Rptr. 287 (1969), the court approved an instruction which informed the jury that an "arrestee may stand his ground and defend himself if he has a reasonable basis for believing that serious bodily injury is about to be inflicted upon him”.
. The court and counsel were referring to the landmark United States Supreme Court case of Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963), in which the Court announced for the first time the now established constitutional duty on the part of the prosecution to disclose exculpatory information to the defense.
. See, e.g., Davis v. Alaska, 415 U.S. 308, 94 S.Ct. 1105, 39 L.Ed.2d 347 (1974).
. Appellant does not explain nor do we see any possible connection between the IAD investigation and the statements given during the course of it and the officers’ potential exposure to civil suit.
. The statements have been forwarded in sealed form to this court and made part of the record. Our inspection of them has led this court to conclude that the trial court’s evaluation of the statements was correct, and that his failure to turn them over to defense counsel was harmless error. However, a reviewing court eyes evidence from a neutral stance and not from the perspective of a defense advocate. Therefore, a remand is necessary.