There's a bit of an internet buzz this week around a video of a law lecture on why you should never, ever, ever, ever talk to the police. The video begins with the law professor and criminal defense attorney, who is a good speaker, making that case, and then a police detective, interesting but not quite as eloquent, agreeing with him and describing the various tricks the police use every day with people stupid enough to talk to them.

The case is very good. In our society of a zillion laws, you are always guilty of something, and he explains, even if you're completely innocent, and you tell nothing but the truth, there are still a lot of ways you could end up in jail. Not that it happens every time, but the chance is high enough and the cost is so great that he advocates that you should never, ever talk to the police. (He doesn't say this, but I presume he does not include when you are filing a complaint about a crime against you or are a witness in a crime against others, where the benefits may outweigh the risk.)

Now fortunately for the police, few people follow the advice. Lots of people talk to the police. Some 80% of cases, the detective declares, are won because of a confession by the suspect. Cops love it, and they will lie (and are permitted to lie) to make it happen if they can.

But since a rational person should never, ever, under any circumstances talk to the police, this prevents citizens from ever helping the police. And there are times when society, and law enforcement, would be better if citizens could help the police without fear.

What if there existed a means for the police to do a guaranteed off-the-record interview with a non-suspect? Instead of a Miranda warning, the police would inform you that:

"You are not a suspect, and nothing from this interview can be used against you in a court of law."

First of all, could this work? I believe our laws of evidence are strong enough that actual quotes from the interview could not be used. To improve things, you could be allowed to record the interview, or the officer could record it but hand you the only copy, and swear it's the only copy. It could be a digitally signed, authenticated copy, which can never be taken from you by warrant or subpoena, or used even if you lose it, perhaps until some years after your death.

However, clearly if the police learn something in the interview that makes them suspect you, they will try to find ways to "learn" that again through other, admissible means. And this could come back to bite you. While we could have a Fruit of the poisonous tree doctrine which would forbid this, it is much harder to get full rigour about such doctrines. Is this fear enough to make it still always be the best advice to never speak to the police? Is there a way we could make it self to assist the police?

I will note that if we had a safe means to assist the police, it would sometimes "backfire" in the eyes of the public. There would be times when interviewees would (foolishly, but still successfully) say "nyah, nyah, I did it and you can't get me" and the public would be faced with the usual confusion over people who are let free even when we know they are guilty. And indeed there would be times when the police learn things in such interviews and could have then found evidence, but are prohibited from, that get the public up in arms because some rapist, kidnapper, murderer or even terrorist goes free.