When did failure to tweet a boisterous crowd become a crime - a felony, no less?

Last week, Nassau Police Department officials say.

About 3,000 young people and their parents showed up Friday at Roosevelt Field to see 15-year-old Canadian pop singer Justin Bieber.

But as the crowd became unruly and safety concerns erupted, police said the event could not go on. Bieber was told to stay away but some fans insisted he had used his Twitter account to say he was on his way.

Police then asked James A. Roppo, an executive from Bieber's label, Island Def Jam Records, to send a Twitter message telling fans to go home and that Bieber was not coming. After Roppo refused, police arrested him.

Police charged Roppo, 44, of Hoboken, N.J., with a slew of misdemeanors and one felony - second-degree assault. Police say an officer slightly injured his shoulder trying to subdue two girls and blamed Roppo. "He would not do as we requested," said Det. Sgt. Anthony Repalone, a Nassau Police spokesman.

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"It might be unprecedented, but it certainly meets the criteria for the charges."Not so fast, said Jonathan Ezor, director of the Institute for Business, Law and Technology at Touro Law School in Central Islip. Ezor said the police attempt to go high-tech might have violated the First Amendment. "The police were essentially requiring a citizen to speak, and just as government may not suppress speech, generally they may not require it either," he said.

Roppo's lawyer, Scott Leemon of Manhattan, said: "I believe my client is being made a scapegoat for the county's and the mall's lack of preparedness for the event." But a mall spokesman said the mall was prepared for the event and a security plan was in place.