The Federal Housing Finance Agency last week filed suit against the city of Chicago claiming that its attempt to enforce a recently amended vacant buildings ordinance on properties owned by Fannie Mae and Freddie Mac impermissibly encroaches on the FHFAs role as sole regulator of the GSEs.Filed in the U.S. District Court for the Northern District of Illinois, the FHFAs lawsuit on behalf of the two GSEs seeks to prevent the city from enforcing the ordinance which requires mortgagees to pay a $500 registration fee for vacant properties and requires monthly inspections of mortgage properties to determine if they are vacant. "The ordinance would impose on the enterprises the responsibilities, but not the benefits of ownership of vacant property on which they hold the mortgage, said the FHFA in a statement. The ordinance would create risks and liabilities for the enterprises at a time when they are already supported by taxpayers, including those in the city of Chicago.