Legal Question in Employment Law in California

Of course. They can demand, you can refuse. They can terminate.

In general, in CA, unless an employee is civil service, in a union, or has a written employment contract, they are an 'at will' employee that can be disciplined or fired any time for any reason, with or without �cause�, explanation or notice.

There is a good argument that if they make it a job requirement, that they should pay the differential, but it is an 'argument' not a 'law'.