One of the more interesting things about crime and justice is how the Fifth Amendment privilege against self-incrimination works in the US:

If you are a defendant in a criminal trial, you don't have to take the stand and testify under oath, because you could be compelled to testify against yourself. Most defendants are smart enough not to take the stand, and let their lawyers do the arguing. Juries don't hold it against them that they didn't testify--jurors have seen all those cop-and-lawyer movies, and know how prosecutors tear into witnesses.

But, if you're subpoenaed before an investigative body (like the Senate committee that called Michael Corleone in GFII), you must be sworn in and testify. Your Fifth Amendment privilege extends only to refusing to answer specific questions. And then you must say, "I refuse to answer that question because my answer might tend to incriminate me." Well, if Michael had "taken the Fifth" when asked, "Were you respnsible for devising the murders of the heads of the Five Families in 1950 [sic]," his answer would have blown his "legitimate" cover--he'd be admitting, under oath, that a truthful answer would tend to incriminate him because he was responsible. So, an investigative body could easily destroy a racketeer's "legitimate" cover simply by forcing him to "take the Fifth" when asked a series of embarrassing questions.

Another twist: A prosecutor can offer a key witness "immunity to testify" and force him to take the stand. Suppose you were a big-time bank robber and you hired small-time me to drive the getaway car, and you killed someone in the bank while robbing it. The cops arrested both of us, and I was charged with being an accessory to murder because I was involved (by driving you away). The prosecutor will tell me that, if I agree to testify against you, I won't be prosecuted on the accessory charge. But if I refuse, I can be held in contempt of court. Why? Since the prosecutor made me "immune" on the accessory charge if I testified, I have no reason to claim that testifying would make me incriminate myself.

Oli, why is taking the Fifth a "privilege"? I thought it's a right, since it's in the Constitution. A driver's license is a "privilege."