You have a right to be present at every stage of your trial

The Supreme Court of the United States hold that the "most basic of rights guaranteed by the Confrontation Clause is the accused's right to be present in the courtroom at every stage of his trial." Lewis v. U.S. 146 US 370.  

The Supreme Court, however, did not make such a right absolute.  In Illinois v. Allen (397 US 337), the Court stated, "A defendant can lose his right to be present at trial if, following the judge's warning that he will be removed if his disruptive behavior continues, he nevertheless insists on conducting himself in such a disruptive manner that his trial cannot proceed if he remains in the courtroom. He can reclaim the right to be present as soon as he is willing to comport himself with decorum and respect."

Not an Absolute Right to Be Present 

The Court laid some loose ground rules and gives discretion to the trial judge to make a judgment, 

A trial judge confronted by a defendant's disruptive conduct can exercise discretion to meet the circumstances of the case, and though no single formula is best for all situations, there are at least three constitutionally permissible approaches for the court's handling of an obstreperous defendant: (1) bind and gag him as a last resort, thereby keeping him present; (2) cite him for criminal or civil contempt; or (3) remove him from the courtroom, while the trial continues, until he promises to conduct himself properly.

I have, pursuant to my duties as a Bucks County criminal defense lawyer, almost encountered such issues.  I had represented a woman with a very difficult demeanor and temper.  After initial outbursts and admonition by the judge, my client calmed down significantly.