NEW YORK - Mayor Michael Bloomberg's administration is taking its first step in appealing a federal judge's ruling to impose reforms to the NYPD's stop-and-frisk policy.

The Law Department filed a notice of appeal Friday in U.S. District Court in Manhattan, challenging the appointment of a federal monitor to oversee the department and ensure that all street stops are conducted legally.

Judge Shira Scheindlin sided with many stop-and-frisk opponents Monday when she said that the police tactic violated the constitutional rights of some New Yorkers.

Bloomberg called the ruling unfair, and says it could set back the NYPD's progress in fighting crime. His administration also plans to ask for a stay of the judge's order until the appeal is heard.

Lawyers now have about three months to file the formal brief.