An anti-graffiti bill introduced yesterday in the City Council will face a challenge from a pro-graffiti lawyer who won a battle to get a similar law suspended in federal court last year.

Daniel Perez, who is backed by the designer and graffiti advocate Marc Ecko, said the new bill, which would ban anyone under the age of 21 from carrying loose spray paint or broad tipped markers, is unconstitutional.

“Criminalizing legal behavior is always a bad idea,” Mr. Perez said. “Presuming that 18-, 19-, and 20-year-olds who are walking around with markers are breaking the law is about as un-American as it gets.”

The chairman of the City ‘s Council’s public safety committee, Peter Vallone Jr., a steadfast opponent of graffiti and the leading proponent of the new law, said he was not surprised that Mr. Perez would fight the revised bill.

“If he is going to argue that students need immediate access to spray paint on the street, then that exposes what this lawsuit was going to do from the beginning: defend the rights of vandals to destroy our city,” Mr. Vallone said.

Mr. Perez led a successful push in U.S. District Court to have a temporary injunction put on a law passed in 2005 that barred people under 21 from possessing “graffiti tools.”

The bill was rewritten in a joint effort by Mr. Vallone and several city agencies to address the court’s constitutional concerns.

“We have worked together to tailor the bill more narrowly, so that it may provide a strong enforcement tool against this destructive crime while comporting with the Court’s findings,” the assistant commissioner of intergovernmental affairs for the police department, Susan Petito, said yesterday at a council hearing on the legislation.

Since 2005, the police department has made 1,135 arrests of people between the ages of 18 and 20 for graffiti crimes, according to police statistics.

The City Council will vote later this month on the new bill.