delivered the opinion of the Court.
A special court-martial composed of officer members convicted appellant, contrary to her pleas, of wrongfully using marijuana, in violation of Article 112a, Uniform Code of Military Justice, 10 USC § 912a. The adjudged and approved sentence provides for a bad-conduct discharge and reduction to the lowest enlisted grade. The Court of Criminal Appeals affirmed the findings and sentence. 50 MJ 584, 591 (1999). Our Court granted review to determine whether the military judge abused his discretion by permitting the prosecution to introduce evidence that appellant used marijuana a second time after the *467offense for which she was tried. For the reasons set out below, we reverse.1
Factual Background
Appellant is a married staff sergeant with over 14 years of active duty. She was assigned as the noncommissioned officer-in-charge of Information Management at the Office of Special Investigations (OSI) detachment, Tyndall Air Force Base, Florida. On Wednesday, April 24, 1996, OSI Special Agent (SA) Lockwood notified appellant that she had been randomly selected for urinalysis testing. She was told to report for testing the next morning. Shortly after she was notified, appellant told SA Lockwood that she felt ill, and she went home early. On the next day, she called SA Lockwood and told him that she was still ill. She returned to duty on Friday, April 26.
On Monday, April 29,1996, she reported to the urinalysis-testing site and provided a urine sample. The sample tested positive for marijuana with a concentration level of 57 nanograms per milliliter. Appellant was ordered to provide another sample, and she provided the second sample on May 21. This command-directed sample also tested positive with a concentration level of 45 nanograms per milliliter.
At trial, during the defense case-in-chief, appellant introduced several affidavits attesting to her good military character, and she testified about her military career. Regarding the first positive urinalysis, she testified as follows:
Q. And you’ve seen the documents from the laboratory and you are aware, I know, the Government has charged you with wrongful use of marijuana between on or about 1 April 1996 and 29 April 1996, you are aware of that?
A. Yes, sir.
Q. Did you do that?
A. No, sir.
Q. Well, let me ask you a question then; do you have any idea how the results came back positive on you?
A. No, sir, I do not.
Q. Is there anything at all?
A. No, sir.
Q. What — has this pending court-martial affected you in any way?
A. Yes sir. They took away my security clearance and my job.
Q. How do you feel about the fact that this test has identified you as having *468used marijuana during the time frame; how does that make you feel?
A. Mad.
Q. Has it affected the way that you relate with people in your unit?
A. Yes, sir.
Q. Has it affected the way you relate with your family?
A. Yes, more stressed.
Following this testimony, trial counsel asked for an evidentiary hearing without the members present. See Art. 39(a), UCMJ, 10 USC § 839(a). At this hearing, he argued that appellant had opened the door for the results of the later command-directed urinalysis to be admitted as impeachment evidence.
The military judge agreed. He ruled that the evidence obtained on May 21 through the command-directed urinalysis was admissible to impeach appellant’s testimony that she did not use marijuana at any time between April 1 and April 29. He also ruled that the evidence was relevant and admissible under Mil.R.Evid. 404(b), Manual for Courts-Martial, United States (1995 ed.),2 to show that appellant’s use of marijuana was knowing and conscious. Finally, citing Mil.R.Evid. 403, he ruled that its probative value was “not substantially outweighed by the danger of unfair prejudice, confusion to court members, or anything else.” However, he would not permit any reference to the command-directed urinalysis in rebuttal to or cross-examination of any defense character witnesses. He specifically ruled that Mil. R.Evid. 608, allowing cross-examination about specific instances of conduct when it is probative of truthfulness, was “not a player” in this case.
When the trial on the merits resumed, trial counsel asked appellant if “good military members ... use drugs,” and she responded, “No, sir.” He asked appellant if she provided a urine sample on May 21, 1996, and if that sample tested positive. She responded affirmatively to both questions. Trial counsel asked her if she was “attempting to imply” that she had “innocently ingested marijuana twice within a five-day period,” and she responded, “It’s possible.” On redirect, she testified that she did not know why both urinalysis tests were positive. She was asked, “Did you use marijuana?” She responded, “No, sir.”
After appellant completed her testimony, the military judge allowed trial counsel to present testimony from Dr. Papa, an expert witness, that the positive reading from the command-directed urinalysis could not have been from the same use of marijuana that resulted in a positive reading from the random urinalysis. During an evidentiary hearing without the members present, Dr. Papa testified that the second positive urinalysis was consistent with chronic use of marijuana, i.e., “more than two or three times a week.”
For reasons not apparent from the record, Dr. Papa’s testimony concerning the possibility of appellant’s chronic use was not presented to the members. In response to questions from two court members, Dr. Papa testified that it was not scientifically possible for both urine samples to have tested positive based on a one-time ingestion. Trial counsel did not pursue the theory of chronic use, but proceeded instead on the theory that appellant used marijuana on two separate occasions.
Before Dr. Papa testified, the military judge instructed the members that the evidence of the second positive urinalysis was admissible for “the limited purpose ... to either prove knowledge ... knowing and conscious ingestion and ... an opportunity on her part to use marijuana ... and, I guess I should say, as it may affect your assessment of the credibility of her testimony before you.”
Before the members began deliberations, the military judge instructed as follows:
As I have advised you earlier, some evidence has been admitted for limited purposes in this case, and more specifically, Prosecution Exhibit 14 and testimony re*469lated thereto regarding a urine specimen provided by the accused on or about 21 May 1996, and subsequent urinalysis testing thereof; and that is the tendency of such evidence, if any, to prove the requisite knowledge on the accused’s part or opportunity to commit the alleged offense before this court, or as such evidence may have an impact, if any, on your assessment of the credibility of the accused’s testimony before the court. You may not consider this evidence for any other purpose. And you may not conclude from this evidence that the accused is a bad person, a person of bad moral character, or has criminal tendencies and that she, therefore, committed the offense charged. This evidence was not admitted for that purpose and you may not consider it for that purpose. You may, as I say, use it only for the limited purposes of its tendency, if any, to prove knowledge or opportunity on the accused’s part to commit the offense charged, or its impact, if any, on the credibility and weight you decide to give to her testimony.
Defense counsel did not object to the limiting instruction or request additional instructions.
Discussion
Mil.R.Evid. 404(a) prohibits admission of so-called “propensity evidence.” It provides: “Evidence of a person’s character or a trait of a person’s character is not admissible for the purpose of proving that the person acted in conformity therewith on a particular occasion.” This Court has held that the mere fact that a person had used drugs at times previous to the charged offenses does “not make it more or less probable that” the person knowingly used drugs on the date charged. United States v. Cousins, 35 MJ 70, 74 (1992).
However, Mil.R.Evid. 404(b) permits evidence of “other crimes, wrongs, or acts” to prove facts other than a person’s character, such as “motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident.” This rule was the legal basis for the military judge’s ruling that the command-directed urinalysis in May was admissible to show that appellant’s use of marijuana in April was knowing and conscious.
Evidence offered under Mil.R.Evid. 404(b) must satisfy three tests to be admissible. First, the evidence must “reasonably support a finding by the court members that appellant committed prior crimes, wrongs, or acts.” Second, the evidence must make a fact of consequence more or less probable. Third, the evidence must satisfy the balancing required by Mil.R.Evid. 403, i.e., its probative value must not be “substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the members, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.” United States v. Reynolds, 29 MJ 105, 109 (CMA 1989). The military judge specifically cited Mil.R.Evid. 404(b) and 403 when he ruled that the evidence was admissible.
Mil.R.Evid. 608(b) provides that the credibility of a witness may not be attacked by extrinsic evidence of specific instances of conduct, but a witness may be cross-examined about specific conduct, if it is probative of truthfulness or untruthfulness. The military judge specifically ruled that Mil.R.Evid. 608 was “not a player” in this case. Nevertheless, he permitted trial counsel to cross-examine appellant about the second positive urinalysis.
“The scope of rebuttal is defined by evidence introduced by the other party.” United States v. Banks, 36 MJ 150, 166 (CMA 1992) (citing Michelson v. United States, 335 U.S. 469, 69 S.Ct. 213, 93 L.Ed. 168 (1948); United States v. Baldwin, 17 USCMA 72, 37 CMR 336 (1967); United States v. Sellers, 12 USCMA 262, 30 CMR 262 (1961)). A broad assertion by an accused “on direct examination that he” or she “has never engaged in a certain type of misconduct” may open the door to impeachment “by extrinsic evidence of the misconduct.” United States v. Trimper, 28 MJ 460, 467 (CMA), cert. denied, 493 U.S. 965, 110 S.Ct. 409, 107 L.Ed.2d 374 (1989); see Walder v. United States, 347 U.S. 62, 74 S.Ct. 354, 98 L.Ed. 503 (1954). The military judge ruled that appellant’s testimony that she did not use marijuana at any time between April 1 and *470April 29 opened the door to impeachment by extrinsic evidence that she had marijuana metabolite in her urine on May 21. He specifically cited Trimper in support of his ruling.
The Court of Criminal Appeals held that appellant’s testimony raised the issue of innocent ingestion. But it held that the second, command-directed urinalysis initiated on May 21 did not directly contradict appellant’s testimony that she did not knowingly use marijuana between April 1 and April 29. 50 MJ at 588. The court below held, however, that the second positive urinalysis was relevant to appellant’s credibility and to rebut her evidence of good military character. Id. at 590.
We disagree. Extrinsic evidence of specific acts is not admissible to rebut evidence of good military character. See United States v. Pruitt, 46 MJ 148, 151 (1997). Although cross-examination of character witnesses about specific acts is permissible under Mil.R.Evid. 405(a), “cross-examination should be limited to acts that would have occurred prior to the crime charged, because the court wants to test character at that time.” Stephen A. Saltzburg, Lee D. Schinasi, and David A. Schlueter, Military Rules of Evidence Manual 572 (4th ed.1997) (emphasis in original). We note that the military judge did not instruct the members on this theory of admissibility.
A military judge’s ruling on admission of evidence will be overturned only if there is an abuse of discretion. A military judge abuses his discretion if his ruling “is influenced by an erroneous view of the law.” United States v. Sullivan, 42 MJ 360, 363 (1995).
We hold that the military judge abused his discretion when he admitted the evidence of the second command-directed urinalysis. This Court has rejected the notion that evidence of an unlawful substance in an accused’s urine at a time before the charged offense may be used to prove knowing use on the date charged. See Graham, 50 MJ at 60; see also Cousins, 35 MJ at 74. We also reject the notion that evidence of an unlawful substance in an accused’s urine after the date of the charged offense and not connected to the charged offense may be used to prove knowing use on the date charged. The military judge’s error in admitting the evidence was compounded by his instruction telling the members that they could consider the evidence as proof of knowledge," knowing and conscious ingestion, and opportunity.
Our dissenting colleague suggests that the evidence of the second positive urinalysis was admissible to prove guilty knowledge under the “doctrine of chances.” This doctrine posits that “it is unlikely that the defendant would be repeatedly innocently involved in the similar suspicious situations.” 1 E. Imwinkelried, Uncharged Misconduct Evidence § 5:28 at 78 (1999).
While we have no quarrel with this theory of admissibility, there is no factual predicate for applying it in this case. Furthermore, under the doctrine of chances, the proponent of the evidence would be required to show that the subsequent ingestion of marijuana was under circumstances sufficiently similar to the first ingestion as to justify an inference that the first ingestion of marijuana was knowing. Id. at 79-80. See United States v. Aguilar-Aranceta, 58 F.3d 796, 799 (1st Cir.1995) (similarity between uncharged act and current charges is “touchstone” in test for relevance); United States v. Mayans, 17 F.3d 1174, 1183 (9th Cir.1994) (prosecution must show more than “the crudest sort” of similarities between charged and uncharged misconduct); United States v. Gordon, 987 F.2d 902, 908-09 (2d Cir.1993) (abuse of discretion to admit evidence of other acts if the other act or acts are not “sufficiently similar to the conduct at issue” to provide reasonable basis to infer knowledge).
In appellant’s case, the prosecution proceeded on a “paper case,” producing laboratory reports but absolutely no evidence of the circumstances surrounding either the first or second alleged ingestion. The record is devoid of evidence that the circumstances of the second alleged ingestion were similar to the *471first. Without such evidence, there is no factual basis for applying the “doctrine of chances.” Accordingly, we conclude that a theory of relevance based on the “doctrine of chances” is not applicable to this case.
Court members are presumed to follow the military judge’s instructions. United States v. Holt, 33 MJ 400, 408 (CMA 1991). Thus, we must presume that the court members considered the evidence of the second urinalysis for an improper purpose.
The military judge also instructed the members that the second positive urinalysis could be considered in their assessment of appellant’s credibility. He gave them no further guidance. Since the military judge rejected Mil.R.Evid. 608 as a basis for admitting the evidence, ruled that the prosecution would not be allowed to attack appellant’s character evidence by cross-examination about specific acts, and specifically cited Trimper in support of his ruling that the evidence was admissible, it is clear that he intended that the members consider the second urinalysis as evidence contradicting appellant’s carefully limited denial that she used marijuana between April 1 and April 29, the period charged. However, the military judge did not translate his rationale into instructions setting out the permissible legal framework for evaluating appellant’s credibility. See United States v. Harper, 22 MJ 157, 164 (CMA 1986) (“Where members are the finders of fact, it is incumbent on the military judge to clearly instruct them concerning [the applicable] principles of law.”) We agree with the court below that the evidence obtained through the command-directed urinalysis does not contradict appellant’s direct testimony. Thus, to the extent that the military judge’s instructions permitted the members to consider the second urinalysis as impeachment by contradiction, they were inadequate and incorrect.
Given the highly inflammatory nature of the evidence of appellant’s second positive urinalysis, the danger of a conviction improperly based on propensity evidence required carefully crafted limiting instructions. Similarly, once appellant put her credibility on the line, she was entitled to have it evaluated in a correct legal framework. In this ease, the military judge admitted the evidence on an incorrect legal basis and submitted it to the members with erroneous and ambiguous instructions. Accordingly, we must reverse.
Decision
The decision of the United States Air Force Court of Criminal Appeals is reversed. The findings of guilty and the sentence are set aside. The record of trial is returned to the Judge Advocate General of the Air Force. A rehearing may be ordered.
. This Court granted review of the following issues:
I
WHETHER THE AIR FORCE COURT OF CRIMINAL APPEALS IMPROPERLY APPLIED THE ABUSE OF DISCRETION STANDARD OF REVIEW BY CONSIDERING APPELLANT’S GOOD CHARACTER AFFIDAVITS — EVIDENCE THE MILITARY JUDGE DID NOT CONSIDER — IN DETERMINING WHETHER THE DEFENSE OPENED THE DOOR TO ADMISSION OF APPELLANT’S COMMAND-DIRECTED URINALYSIS.
II
WHETHER THE AIR FORCE COURT OF CRIMINAL APPEALS ERRED BY NOT STRICTLY APPLYING MIL.R.EVID. 311(b) WHILE SIDESTEPPING THE QUESTION OF WHETHER THE RESULTS OF APPELLANT’S COMMAND-DIRECTED URINALYSIS WERE ILLEGALLY SEIZED EVIDENCE UNDER THE FOURTH AMENDMENT.
III
WHETHER ADMISSION OF THE RESULTS OF APPELLANT’S COMMAND-DIRECTED URINALYSIS IN HER COURT-MARTIAL VI-
OLATED HER FOURTH AMENDMENT RIGHTS TO BE FREE FROM UNLAWFUL SEARCH AND SEIZURE.
IV
WHETHER THE MILITARY JUDGE'S RULING THAT APPELLANT OPENED THE DOOR TO ADMISSION OF APPELLANT’S COMMAND-DIRECTED URINALYSIS UNDER MIL.R.EVID. 311(b) WAS AN ABUSE OF DISCRETION.
V
WHETHER THE AIR FORCE COURT OF CRIMINAL APPEALS ERRED WHEN THEY CONCLUDED APPELLANT RAISED THE "UNKNOWING INGESTION” DEFENSE, CONTRARY TO THIS HONORABLE COURT’S OPINION IN UNITED STATES V. GRAHAM, 50 MJ 56 (1999).
VI
WHETHER THE ADMISSION OF APPELLANT’S COMMAND-DIRECTED URINALYSIS UNDER MIL.R.EVID. 404 WAS AN ABUSE OF DISCRETION.
Since we reverse on the basis of Issue IV, we do not address the other issues.
. All Manual provisions are cited to the version applicable at trial. The 1998 version is unchanged, unless otherwise indicated.