Legal Question in Constitutional Law in Colorado

With few exceptions, witnesses who are properly subpoenaed must testify in a criminal trial. And yes, the testimony can be used against the witness later, either in the same case or in another.

Witnesses can invoke the Fifth Amendment. It happens often. But they may only do so if there is an actual risk of being charged with a crime. They can't do it just to avoid answering questions they want to avoid.

If you think this is a risk, you should get a lawyer before you testify. If you can't afford one, call your local public defender's office to see what options are available. The court should appoint a lawyer for you if you can't pay for one, but deciding whom to appoint may be difficult if the local public defender's office is already involved in the case.

Good luck.