No, a person on trial for a crime doesn't have to testify if they choose not to do so. In fact, depending on the case, attorneys will often advise their client not to testify.
Anyone who is sued is allowed to testify at trial for a calim against him or her.
Your question is unclear. In the USA, a defendant does NOT HAVE TO testify at his trial, ever. The defendant is the one accused of committing the crime. He does not have to say anything (OJ Simpson did NOT testify in his first trial, Scott Peterson did NOT testify at his trial.) The Prosecutor will present his case (with all his evidence and witnesses) explaining to the jury (or judge) WHY the evidence shows the defendant committed the crime. The Defense Attorney will present his case (with all his evidence and witnesses) explaining to the jury (or judge) WHY the evidence does NOT show the defendant committed the crime. The defendant does not have to be one of those witnesses. He cannot be forced to testify.
They can't. Only subpoeana'd witnesses may testify at a trial or hearing.
a fair trial
Yes.
No one can be tried for the same crime twice and one does not have to testify against himself/herself in a trial.
You have the right to not testify if you're the one on trial, as well as the right not to incriminate your self. But once you decide testify you have to go through with it. you cant decide you don't like a question and not answer it. Either your all in or all out there is no in-between
Yes, only legally married spouses are protected from being forced to testify against one another.
Yes.
Yes AA Not in the United States
true
Maryland v. Craig