A law firm is demanding the city leaders lift the controversial ban on food trucks in Denver’s Lower Downtown nightlife district, arguing that the mobile food vendors actually make the neighborhood safer. The firm’s lawyers say the ban is not only a bad policy but may also be unconstitutional. The Institue for Justice, a Virginia-based, nonprofit law firm, sent a letter to Denver City Council members on Wednesday urging the “repeal” of the ban that bars food trucks from portions of Market, Blake and Larimer streets between 18th and 22nd streets on Thursday, Friday and Saturday nights. The letter also offers help.