11 N.Y.2d 274, 183 N.E.2d 319 (1962)
Defendant Young, aged 40 and regularly employed with a clean record except for an $8 fine from 19 years earlier, observed two middle-aged men beating and struggling with an 18-year-old youth at 3:40 p.m. on October 17, 1958, in front of 64 West 64th Street in Manhattan.1 Believing the youth was being unlawfully assaulted, Young went to his rescue by pulling on or punching at the seeming assailants.2 In the ensuing affray, one of the older men got his leg locked with that of Young and when Young fell the man’s leg was broken at the kneecap.3
The two men were detectives in plain clothes seeking to arrest the youth for disorderly conduct after he had resisted their efforts.4 The injured man then pulled out a revolver, announced to Young that he was a police officer, and placed him under arrest.5
At trial, Young testified that he had known nothing about what had happened before he came upon the scene, that he had gone to the youth's aid because the youth was crying and trying to pull away from the middle-aged men, and that the older men had almost pulled the trousers off the youth.6 The only detective who testified stated that Young did not know and had no way of knowing that they were police officers or that they were making an arrest.7
Young stands convicted of assault in the third degree, for which he received a sentence of 60 days in the workhouse, the execution of such sentence being suspended.8
Whether one is criminally liable for assault in the third degree if he goes to the aid of another who he mistakenly, but reasonably, believes is being unlawfully beaten, and thereby injures one of the apparent assaulters?9
With respect to intent crimes, under general principles, a mistake of fact relates as a defense to an essential element of the crime, namely, to the mens rea.10
No. Assault in the third degree is an intent crime requiring a general intent to commit an unlawful touching.11 Young's mistake of fact was reasonable because he had no knowledge that the two men were plain-clothes detectives making a lawful arrest of the youth, and therefore the mens rea element is negated.12
Defendant Young is not criminally liable for assault in the third degree.13
Related opinions on this issue
Justice Valente dissents and would affirm the conviction because the intent to commit a battery was unquestionably proven.14 Since there was no relationship between defendant and the person whom the police officers were arresting, defendant acted at his peril in intervening and striking the officer.15 Under well-established law, defendant’s rights were no greater than those of the person whom he sought to protect.16
Since the arrest was lawful, defendant was no more privileged to assault the police officer than the person being arrested.17