Detroit Police Chief Ralph Godbee announced the shift plan earlier this month but the Detroit Police Officers Association went to court and got the order to stop it.
A Wayne County Circuit Court hearing Thursday morning ended with the order being thrown out and the DPOA complaint dismissed.
It wasn't immediately known when the 12-hour shifts would begin.
Godbee wants to impose 12-hour work days for most Detroit police officers, excluding those in narcotics, gang squad and homicide. The officers would work two 12-hour days, then get two off before working three days and getting three days off.