Employee terminated when returning to work following incarceration?

My husband was arrested for a non-violent crime on his way to work. He ended up spending about a month in county jail. During this time, I contacted his supervisors, union rep and scheduling department every single day, including his days off just in case, to notify them that he would not be able to work that day due to legal reasons and uncertain as to when he would return. I even put in a verbal request for an emergency personal LOA with no response. After his release he returned to work and was put back on the schedule for the remainder of the month. On his third day returning to work, about a week after his first day returning, he was terminated for "no-call, no-show" for the time he was in jail. My questions has two parts. What is the legality of allowing an employee to work shifts and then firing them later for a previous incident and shouldn't my daily contact with his employer and union rep, (all recorded), be sufficient to protect him against termination from "no-call, no show".? A little background- he has worked for this medical facility for 8 years, has no prior convictions and the charges/ are in no way significant or related to the duties of his job. Thank you