I have to write a theoretical paper for my criminal justice class and I was wondering if the myth about a cop revealing himself when asked? The theoretical situation I was thinking of was this: An undercover cop goes up to a guy and ask for a bag of marijuana; the man tells him that he doesn’t talk to lawyers, prosecutors, cops, federal or authorative officials of any kind. He then asks the guys if he falls into that category in any sense of the word. Does the cop have to reveal himself or not? Thank you for the help.
Watching prostitute stings on COPS, it seems the hooker always asks if the John is a cop, and he lies, she gets arrested.
No.
But I’m judging by my extensive knowledge of Law & Order. I suppose you want a fancy citation that doesn’t come from television. So I’m really wasting both of our time here.
No.
Why would he?
Snopes says no:
http://www.snopes.com/risque/hookers/cop.htm
Well, it seems like if it were true there would hardly ever be a successful undercover sting, because all a criminal would have to do is say the “magic words” for it to be ruined. There are also situations in which it could be very dangerousfor a police officer to have to identify themselves as such.
Until you are actually under arrest, they can lie to you all that they want. I learned this first hand when I did a “ride along” with a cop a few years ago. Long story short, he told a woman that her crime was caught on tape which was a complete fabrication. Based on this, she admitted the crime and was arrested.
Haj
This has been done many times on the SDMB before and the answer is “No.” That myth began as a twisting of the entrapment laws.
OH!
Is this ever a lead-in to a dirty joke! 
In fact, they can also lie to you AFTER you are arrested.
In the story above, the polcie could have arrested the woman (assuming they had probable cause to do so) and then told her her crime was caught on tape.
- Rick
In addition, the Oldest Trick in the Book, when two people are arrested for the same crime, is to tell each of them, “Come on, your friend already confessed. If you cooperate you can get off easy.”
One of my favorite criminal procedure cases involves similar legal lore. In Hawaii, the police decided to sting some escort services. They hired an “investigator” who engaged the services of the escorts. After the transactions were completed, the escorts were arrested, charged, and convicted of prositution. The Hawaii Supreme Court upheld the convictions.
Check the link in my .sig for another intersting discussion of this issue …
Might want to post your sig if you want us to review it…