It's a warning, no matter where you are your statements will be used against you in a court of law but in America we require the police to warn everyone about that. It's not a catch 22, if you keep your mouth shut and get a lawyer then you will usually walk unless you were caught red handed, even in that case you will probably get less time if you shutup and lawyer up.
And if you actually didn't commit a crime and you stay shut and lawyer up you will almost always be vindicated.