A lawsuit filed Wednesday by three college faculty unions is challenging an arbitration ban that the state put into law last year, and has since led to at least five termination decisions that cannot be questioned. The United Faculty of Florida, the statewide faculty union representing more than 25,000 faculty and graduate employees, along with its chapters at Florida State University and the University of Florida, have filed a case against the Board of Governors and the two schools’ boards of trustees in the Northern District of Florida, claiming the ban is “a politicized attempt to stifle Florida faculty members’ academic freedom.”