dissenting. The majority reverses the habeas court on the sole ground that the court abused its discretion in not allowing the respondent, the warden of the state prison (state), to call the trial judge, Judge William J. Lavery, to testify as to his observations of the petitioner, Murray Gold. The state sought the trial judge’s testimony as evidence to establish that the petitioner was competent to stand trial a fourth time for the murder of his former in-laws.
An accused is not competent to stand trial “if he is unable to understand the proceedings against him or to assist in his own defense.” General Statutes § 54-56d (a). At the habeas hearing, the petitioner claimed that he was incompetent to stand trial for a fourth time because he was unable to assist in his own defense. “Of the objectives sought to be achieved by a determination of a person’s sanity for purposes of standing trial, historically the foremost has been said to be the protection of the accuracy of the adjudication involved; the competency rule . . . is claimed to have been designed to ensure that the defendant is able to provide his counsel with the data necessary or relevant to the struc*322turing of a defense.” State v. Pastet, 169 Conn. 13, 26, 363 A.2d 41, cert. denied, 423 U.S. 937, 96 S. Ct. 297, 46 L. Ed. 2d 270 (1975). According to the majority, the trial judge’s testimony regarding his observations of the petitioner’s demeanor and alertness during the course of the trial was necessary on the issue of whether the petitioner was competent to aid in his own defense.
The majority relies in part on Woodward v. Waterbury, 113 Conn. 457, 155 A. 825 (1931), for its conclusion that it was improper to exclude the trial judge’s testimony. The majority, however, ignores an important rule set forth in Woodward, to wit: “Counsel should never summon [the trial judge to testify] if the rights of their clients can be otherwise protected.” Id., 465. Since other witnesses for the state testified, and could have testified as to the petitioner’s demeanor and alertness during the trial, there surely was no “compelling need” for Judge Lavery’s testimony. This same evidence was or could have been obtained from other sources, for example, Walter Scanlon, the assistant state’s attorney, William Collins, the petitioner’s attorney at his fourth trial, Nicholas Serignese, cocounsel with Collins, any of the other attorneys present, or any of the courtroom personnel, such as the clerk, court reporter or sheriff.
Furthermore, the inclusion or exclusion of evidence by the trial court is within the court’s broad discretion. Recently, in State v. Steiger, 218 Conn. 349, 373, 590 A.2d 408 (1991), with Justice Callahan writing for the unanimous court, this court held that “[b]ecause the admissibility of the [evidence] was an evidentiary question, we cannot reverse the decision of the three judge panel to admit the [evidence] unless we conclude that the panel abused its discretion or committed a clear error involving a misconception of the law.” Assuming that the habeas court abused its discretion in not allowing the trial judge to testify, the majority does *323not observe the established standard of review that the appellant bears the burden of establishing, not only that the trial court’s ruling was erroneous, but also that the ruling was probably harmful. “Evidentiary rulings will be overturned on appeal only where there was an abuse of discretion and a showing by the [appellant] of substantial prejudice or injustice.” (Emphasis added; internal quotation marks omitted.) State v. Alvarez, 216 Conn. 301, 306, 579 A.2d 515 (1990); see also State v. Brown, 199 Conn. 14, 25, 505 A.2d 690 (1986). Indeed, as Justice Callahan wrote for a unanimous court in State v. Jackson, 198 Conn. 314, 319, 502 A.2d 865 (1986), “[e]very reasonable presumption should be given in favor of the correctness of the court’s ruling in determining whether there has been an abuse of discretion. Reversal is required only when an injustice appears to have occurred.” (Internal quotation marks omitted.)
Although the state established the purpose for calling the trial judge, which was to prove that the petitioner was, in fact, alert and could have been of assistance to his own defense, the state failed to prove that the exclusion of his testimony was harmful.1 First, the state already had on the record Judge Lavery’s observation that the petitioner was alert. When Scan-*324Ion told the trial judge that he thought the petitioner was sleeping, the trial judge replied: “No, the record will note that he, the defendant, is awake.”2
Second, the habeas court had the benefit of the testimony of Collins on the demeanor and alertness of the petitioner during the trial. Collins testified that he “knew that [the petitioner] was taking a level of medication sufficient to assist . . . in his defense, and [that the petitioner] continuously knew at that time the nature of the proceedings against him.” Collins also testified that he had “a good professional, close relationship” with the petitioner throughout the trial. He stated that there was never a time when he believed that the petitioner was unaware of the court proceedings. Collins asserted that the petitioner actively participated in the jury selection process and that prior to trial, the petitioner discussed defense strategy with Collins.
Therefore, the trial judge’s testimony would only have been repetitive and cumulative of the testimony that the petitioner had been alert diming the trial. In sustaining convictions, we have long held that the erroneous exclusion of testimony that is merely repetitious or cumulative is not harmful error. See State v. Person, 215 Conn. 653, 664-65, 577 A.2d 1036 (1990), cert. denied, 498 U.S. 1048, 111 S. Ct. 756, 112 L. Ed. 2d 776 (1991) (erroneous exclusion of cumulative evidence did not have a prejudicial impact on the outcome of the trial); State v. Robinson, 213 Conn. 243, 260, 567 A.2d 1173 (1989) (erroneous inclusion of cumulative evidence was not harmful); State v. Jones, 132 Conn. 682, 683, 47 A.2d 185 (1946) (it was within the trial court’s discretion to refuse to permit questioning that had been “asked and ruled upon on several occasions”).
*325Third, Scanlon was called by the petitioner to testify at the habeas hearing. Scanlon testified that, in his opinion, no “gross injustice” had been done to the petitioner. Because of Scanlon’s continuing presence throughout the trial and his close proximity to the petitioner, the state could have taken the opportunity during its cross-examination to question Scanlon further on his observations as to the petitioner’s alertness.
Finally, it is clear to me that the habeas court did not rely upon Attorney John Williams’ momentary observation of the petitioner, but rather upon the substantial professional testimony of Dr. Walter Borden, a prominent psychiatrist, who, during his years of practice, has been involved in at least fifteen cases before this court. Dr. Borden’s testimony must be reviewed within the context of the facts of this case, which are not contested. He testified that the petitioner had a history of treatment for mental illness that dates back to 1974; that between January 22, 1985, and May 20, 1986, the petitioner had been found incompetent to stand trial by state doctors at three competency hearings ordered by the court; and that the petitioner was discharged from the state’s Whiting Forensic Institute (Whiting) in late 1985 with the warning that, although he was then competent, his mental condition had not been “completely ameliorated.”3
*326Dr. Borden concluded that at the time of the fourth trial, the petitioner was not competent to assist in his defense. There were two principal bases for his conclusion. The first basis was that the petitioner’s psychosis rendered him unable to work with counsel. He determined that the petitioner suffered from schizophrenia with depression and paranoia. He testified that as “[p]art of his paranoia, [the petitioner] had paranoid delusions of persecution. Hallucinations in that regard [have] involved the legal system, judges, lawyers [and] his lawyers.”
The petitioner’s background is important to a full understanding of his paranoia and how it affected his competency to assist in his own defense. The petitioner is a survivor of the German holocaust and underlying his paranoia was his confinement in several concentration camps as a child together with his father, mother and sister. When the petitioner was eleven years old, his family escaped from the concentration camp at Auschwitz with the assistance of English rescuers. The petitioner was responsible for his sister, who was eight years old, but during the confusion, she was left behind. The rescuers forbade the petitioner’s family from searching for the girl for fear that they would be discovered by the German guards and executed. As a result of his time in the camps and this traumatic experience, the petitioner developed a syndrome known as survivors guilt, which is particular to concentration camp survivors, hostages or persons who have survived natural disasters. This syndrome manifests itself as massive grief. Dr. Borden pointed out that the petitioner’s “condition was compounded by the fact that his sister [had] perished and ... in his growing up, [he] was feeling responsible for his mother’s sadness.” He testified that “[m]uch of his distrust, which is clearly paranoid, in a way makes sense, if you look at the concentration camp and what the adults — and especially *327[what] the children experienced there. [The petitioner] would not trust a lawyer, certainly, and he was incompetent; and on a long-term basis, he wouldn’t trust anybody, nor would he trust doctors.”
Dr. Borden testified that the petitioner has denied certain aspects of his life as a result of his psychotic condition. He relayed that the petitioner denied his concentration camp experience, denied that he is Jewish, denied that his parents were Jewish, and denied that he had a sister who died. He stated that this kind of denial is called “psychotic denial.” He testified that this is “denial of very basic issues of reality and reality about himself. [The petitioner] had to keep that [reality] entirely out of his awareness.” According to Dr. Borden, these paranoid delusions came out in bizarre ways and extended to his attorneys. He testified that the petitioner considered all his lawyers to be crazy. He reported that the petitioner said that “he didn’t understand [the lawyers]; they didn’t understand him.” Dr. Borden concluded that the petitioner was not able to work effectively with his lawyers in his own defense.
The second principal basis for Dr. Borden’s conclusion was the high dose of medication that the state had prescribed for the petitioner. Although the Whiting diagnostic team cautioned that the petitioner’s mental condition required “some form of continued treatment in order to maintain his competency,”4 the only treatment for his psychosis was an increased daily dose of Navane from the fifteen milligrams prescribed for him while at Whiting, to twenty milligrams given to him at the correctional facility at New Haven. Navane is a major tranquilizer and it is used in schizophrenia treatment to quiet patients and help make them manageable. Dr. Borden testified that the dosage was *328increased without authorization from Whiting or from the court. This higher dosage made the petitioner more apathetic, somnolent and unresponsive. He further testified that the “twenty milligrams for a maintenance dosage of Navane is high. It would tranquilize him no doubt. It would control his behavior. It reflected in the records and my examination, [that it] would interfere with his comprehension, with his awareness, with his ability to respond. It certainly would help him behave in the courtroom if sitting and not creating a disturbance is what is desired and that’s all.” Dr. Borden concluded that as a result of this over medication, the petitioner’s ability to participate in his own defense was impaired.5
Our law is clear that “[t]he conviction of an accused person who is not legally competent to stand trial violates the due process of law guaranteed by the state *329and federal constitutions. Conn. Const., art. I, § 8; U.S. Const., amend. XIV, § 1; see Pate v. Robinson, 383 U.S. 375, 378, 86 S. Ct. 836, 15 L. Ed. 2d 815 (1966). This rule ‘imposes a constitutional obligation, [on the trial court], to undertake an independent judicial inquiry, in appropriate circumstances, into a defendant’s competency to stand trial . . . .’ State v. Watson, [198 Conn. 598, 605, 504 A.2d 497 (1986)]; see Drope v. Missouri, 420 U.S. 162, 180, 95 S. Ct. 896, 43 L. Ed. 2d 103 (1975); State v. DeAngelis, 200 Conn. 224, 242, 511 A.2d 310 (1986). ‘Even when a defendant is competent at the commencement of his trial, a trial court must always be alert to circumstances suggesting a change that would render the accused unable to meet the standards of competence to stand trial’ Drope v. Missouri, supra, 181. This constitutional mandate is codified in General Statutes § 54-56d (a), which provides that ‘[a] defendant shall not be tried, convicted or sentenced while he is not competent.’ ” State v. Gonzalez, 205 Conn. 673, 686-87, 535 A.2d 345 (1987).
We have made it clear, when upholding a conviction, that we will “not presume error; the trial court’s ruling is entitled to the reasonable presumption that it is correct unless the party challenging the ruling has satisfied its burden demonstrating the contrary.” State v. Crumpton, 202 Conn. 224, 231, 520 A.2d 226 (1987). That presumption, however, is not present in this case. Indeed, we have continuously ruled that if the trier of fact has other evidence on the issue, then that weighs heavily against the error being harmful. In State v. Silveira, 198 Conn. 454, 503 A.2d 599 (1986), we held that the exclusion of relevant testimony about the defendant’s state of mind was not harmful. “In light of the additional evidence pertaining to the defendant’s state of mind that was placed before the jury, we do not believe that the erroneous exclusions of evidence deprived the defendant of either his state constitutional *330right to testify or his federal constitutional right to present an effective defense. Because the erroneous exclusions of evidence do not amount to a constitutional violation, it is the defendant’s burden to show that the errors were harmful. State v. Brown, 187 Conn. 602, 611, 447 A.2d 734 (1982); State v. Gordon, 185 Conn. 402, 419, 441 A.2d 119 (1981) [cert. denied, 455 U.S. 989, 102 S. Ct. 1612, 71 L. Ed. 2d 848 (1982)]; State v. Ruth, [181 Conn. 187, 196-97, 435 A.2d 3 (1980)]. In this case we find that this burden has not been met.” Id., 479.
It is particularly troubling that I cannot find anywhere in the majority’s analysis what it uses as the standard of review. From what I can detect from the majority opinion, there is a double standard of review, one for claims of error raised by a defendant and one for reviewing the same claims raised by the state. Furthermore, the majority greatly diminishes the factfinding jurisdiction of the habeas court. The majority concludes that the habeas court’s ruling was pivoted o,n Williams’ testimony, which was supplied by his “brief observation” of the petitioner during a trial that began on June 24,1986, and concluded one month later on July 24,1986. To assume that the mere mention of Williams’ observation in the habeas court’s memorandum of decision must be pivotal is contrary to our law.6 *331It cannot be said that the habeas court’s conclusion “was clearly erroneous.” Myers v. Manson, 192 Conn. 383, 391, 472 A.2d 759 (1984).
I agree with the habeas court’s well reasoned decision that during the fourth trial the petitioner was legally incompetent because he could not assist in his own defense. Accordingly, the petitioner’s conviction violated federal and state constitutional law and the statutory law of this state. The petitioner is entitled to a new trial. I dissent.
Indeed, notwithstanding the assertion of the majority that the testimony was also necessary to “undercut the probative force of . . . Scanlon’s comments,” in its brief the state’s only claim of prejudice from the habeas court’s exclusion of Judge Lavery’s testimony is the following: “The court’s refusal to permit [the] respondent to call Judge Lavery to testify as to his observations was particularly prejudicial, given the habeas court’s undue reliance on the momentary observation by Attorney [John] Williams. Judge Lavery observed the petitioner on a daily basis for a period of months during the fourth trial and would have provided crucial evidence to undercut Attorney Williams’ testimony, which the habeas court obviously considered significant.
“By refusing to allow [the] respondent a fair opportunity to rebut evidence heavily relied upon in its decision, the court committed harmful error. State v. Torres, 210 Conn. 631, 640-645 [556 A.2d 1013] (1989). Accordingly, a new habeas proceeding should be ordered.”
See the majority opinion for the complete colloquy between the trial court and assistant state’s attorney Walter Scanlon.
The report of the diagnostic team at Whiting stated, in part, the following: “We wish to emphasize that this should not be interpreted to mean that [the petitioner’s] mental condition has been completely ameliorated. He suffers from a mental condition, in our opinion, that will require some form of continued treatment in order to maintain his competency over the course of the extended future. . . . Progress in actually obtaining counsel is uncertain due to practical inerts connected with his confinement here and his own financial circumstances. Initiative has been taken in the direction of obtaining counsel, according to our understanding, and a continued program of psychiatric treatment is now advised as a necessary adjunct to the maintenance of his competency.”
See footnote 3, supra.
Dr. Borden testified that as a result of the high dose of Navane administered by the state, the petitioner “had no idea of what was going on. In my examination of him, what he told me was he doesn’t understand why they didn’t bring in the testimony having to do with his shoes, and it was at that point that he was pointed out to be unresponsive, that the testimony had to do with that.
“He told me, in my examination of him, that he was kind of unclear about the trial. He thought it was going to go on, and all of a sudden, it was over. And he said he never got a chance to explain, or to question, or to say-he thought that would come up later about the evidence which he was convinced would exonerate him, and he said all of a sudden, it was over.
“That has to do with the medication, and it does really appear that he was over medicated. I have really more than doubts about that. Why was [it] increased? Why was it increased from fifteen milligrams to twenty milligrams? I mean, I know you don’t increase medication like that in that amount unless there’s a deteriorated mental condition; unless there’s something going on. The timing is such, that it would [be] apt to cause over-sedation. These medications, a medication like Navane, when the dosage is increased, it’s apt to cause sedation for a period of time until there’s— well, at some level, it can just cause over-sedation and apathy, but that’s most apt to occur with a recent change. If you’re upping the dosage, you’re more apt to get sedation in the immediate period after the change—and I’m not talking about hours; I’m talking about days, weeks.”
Indeed, it appears contrary to the state’s position. The state asserted in its brief: “Most of Williams’ testimony involved his relationship with [the] petitioner during the third trial. [The subject matter of the present case is the petitioner's fourth trial.] . . . Williams also testified that, one day during [the] petitioner’s fourth trial, he ‘passed through the courtroom briefly and . . . observed Mr. Gold and his counsel.’ ... As he passed through the courtroom, Williams tried not to be ‘disruptive.’... He testified that [the] petitioner did not appear to be ‘reacting’ to anything going on in the courtroom, including Williams’ presence. ... He stated that [the] petitioner appeared ‘very different from the way he had been during the third trial . . . ’ and that he observed [the] petitioner ‘staring straight ahead.’ . . . Williams testified that he spent‘probably less than five minutes’ passing through the courtroom and that he did not sit down in the courtroom at any point. ...”