Babak Taherzadeh is a troll.



One of his Twitter personas boasts the bio: "im smarter than u unless you are really smart."

He claims he has a "different sense of humor." He peppers his tweets with profanity. He plays an online character, one he says doesn't reflect who he really is.

That character has gotten him into trouble.

Taherzadeh sits in the Dallas County jail, where he has been since June, held on a felony stalking charge. He is accused of using social media to harass a judge who oversaw a criminal case against him.

Before his arrest, he regularly commented online on political issues and public figures.

Taherzadeh believes he was exercising his rights to free speech and to petition the government when he posted negative comments on social media about a state district judge.

But authorities see it differently. They say Taherzadeh's tweets threatened physical harm.

The arrest warrant affidavit says Judge Brandon Birmingham "is in fear for the life of his family and for his own" because of Taherzadeh's messages and social media posts.

In a time when everyone seems to have an online opinion, when people are emboldened by the anonymity of screen names, the case against Taherzadeh shows the limits of free speech.

The First Amendment protects freedom of speech, religion, the press, the right to assemble and to petition the government, and it prevents the government from punishing people who exercise those rights.

And though hate speech is protected, there is a line when a person's safety is threatened, legal experts say.

"It's always been a huge tension there, the concerns about safety versus having an open dialogue and being able to criticize public officials," said Lata Nott, executive director of the First Amendment Center.