(concurring).
I concur in the result. I agree with Judge Stephenson’s conclusion that the trial court in this case properly admitted the evidence of other crimes to show the absence of entrapment. Nevertheless, I feel constrained to add a comment relating to the admissibility of such evidence.
The question of the admissibility of evidence relating to other crimes must be resolved by trial judges on a case-by-case approach after weighing the need for the evidence against the possible prejudice flowing from its introduction. No mechanical rule can be applied in determining its admissibility.1 *111The Proposed Rules of Evidence for the United States District Courts and Magistrates contain an appropriate guideline:
OTHER CRIMES, WRONGS, OR ACTS. Evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show that he acted in conformity therewith. It may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident. [Rule 4.04(b).]
The comment to this subsection reads:
Subdivision (b) deals with a specialized but important application of the general rule excluding circumstantial use of character evidence. Consistently with that rule, evidence of other crimes, wrongs, or acts is not admissible to prove character as a basis for suggesting the inference that conduct on a particular occasion was in conformity with it. However, the evidence may be offered for another purpose, such as proof of motive, opportunity, and so on, which does not fall within the prohibition. In this situation the rule provides that the evidence may be admissible. No mechanical solution is offered. The determination must be made whether the danger of undue prejudice outweighs the probative value of the evidence, in view of the availability of other means of proof and other factors appropriate for making decisions of this kind under Rule 4-03 (a). Slough and Knightly, Other Vices, Other Crimes, 41 Iowa L.Rev. 325 (1956).
This rule and the comment thereto properly emphasize the trial judge’s role of balancing the probative value of such evidence against its prejudicial nature in determining its admissibility.
. McCormick makes the following comment on this subject:
There is an important consideration in the practice as to the admission of evidence of other crimes which is little discussed in the opinions. This is the question of rule versus discretion. Most of the opinions ignore the problem and proceed on the assumption that the decision turns solely upon the ascertainment and application of a rule. If the situation fits one of the classes wherein the evidence has been recognized as having independent relevancy, then , the evidence is received, otherwise not. This mechanical way of handling such questions has the advantage of calling on the judge for a minimum of personal judgment. But problems of lessening *111the dangers of prejudice without too much sacrifice of relevant evidence can seldom if ever be satisfactorily solved by mechanical rules. And so here there is danger that if the judges, trial and appellate, content themselves with merely determining whether the particular evidence of other crimes does or does not fit in one of the approved classes, they may lose sight of the underlying policy of protecting the accused against unfair prejudice. The policy may evaporate through the interstices of the classification.
Accordingly, some of the opinions recognize that the problem is not merely one of pigeon-holing, but one of balancing, on the one side, the actual need for the other crimes-evidence in the light of the issues and the other evidence available to the prosecution, the convincingness of the evidence that the other crimes were committed, and that the accused was the actor, and the strength or weakness of the other crimes-evidence in supporting the issue, and on the other, the degree to which the jury will probably be roused by the evidence to over-mastering hostility. C. McCormick, Evidence 332 (1954).