If contracts allow it...
Presumably they can only do this if the contractor has signed a contract that allows the client to dismiss the contractor. If there's no termination clause, the contract is binding and the contractor can tell them to get lost.
In my last contract the client normally had a termination clause. I had it removed, and they were OK with that. When they later told all contractors to take a pay cut I said no. They told me I was out, until I pointed out they were bound to give me the work at the agreed rate until the contract ended. Naturally, when the contract did end there wasn't a renewal, but since I hated the work and wouldn't have renewed anyway that wasn't a big deal.
If you sign a contract that allows the client to push you around, expect to be pushed around.


