A judge on Thursday temporarily blocked the city from enforcing five gun-control ordinances pending a challenge from the National Rifle Association.
The NRA argues that state law prevents Pennsylvania municipalities from regulating guns, a view that even the city's crime-weary district attorney shares.
"The city has no basis to pass any of these gun-control ordinances and they know it," lawyer C. Scott Shields argued on the NRA's behalf.
City lawyers contend that Philadelphia can pass gun-control ordinances if the laws are outside the scope of state measures. As an example, lawyer Mark Zecca told the judge that one Pennsylvania county had banned guns at its courthouse.
Among other things, the five city ordinances passed April 10 ban the sale of assault weapons; require owners to report a lost or stolen gun within 24 hours; and limit firearms purchases to one a month.
They came in response to the city's one-a-day murder rate and its reputation for being a weapons source for criminals in New York and other states with strict gun laws.
The judge scheduled arguments for April 28. She said she would rule very quickly, although her decision is sure to be appealed by the losing side.
Mayor Michael Nutter, who declared a "crime emergency" shortly after taking office in January, quickly signed the City Council bills into law - despite still-pending litigation over earlier gun-control efforts.