You have lots of latitude to decide the shifts and locations to which employees are assigned. As long as there are no obvious flags (like only assigning members of a particular protected class to the night shift), courts likely won’t interfere with yourdecisions.
Recent case: Chester Williams, who is black, worked as a correctional officer. Management began investigating potential security breaches because someone had been smuggling illicit drugs and cell phones into the prison.
Because management couldn’t pinpoint exactly where the security breaches were, they decided to move staff around. Some correctional officers were transferred to different facilities and different shifts. Williams was one of the transferred employees.
He sued, alleging race bias.
But his claim didn’t go far because the court said he hadn’t suffered an “adverse employment decision.” He hadn’t been fired or demoted. He continued to receive the same pay and benefits. The only difference was that his commute became slightly longer and he had to work the night shift rather than days. Under the circumstances, that wasn’t enough to support a lawsuit. (Williams v. Florida Department of Corrections, No. 3:09-CV-213, SD FL, 2011)
Final note: The court did say that in extreme cases, a transfer or shift change might be an adverse action. For example, if the employee’s new commute was extremely long, that might be enough.
The case might have turned out differently if Williams had alleged retaliation. Remember that retaliation is anything that would dissuade a reasonable employee from complaining in the first place. In the leading Supreme Court case on retaliation, a shift change that interfered with child care duties was enough to constitute retaliation.