The answer provided by a professional philosopher (at AskPhilosophers.org) to the question “If we have no free will, then is the entire legal system redundant since no one can be held accountable for anything since no one has control over their own actions?” would be shocking if my expectations were not already so low.
The level of “free will” required of humans in order to justify legal penalties for behaviour that we wish to prevent is no more than that required of a dog to justify the use of negative reinforcement in its training (and of euthanasia in the case of a dog that is dangerously untrainable) – or that which is required of a computer chip in order to justify callously discarding those that fail their initial start-up tests. If the computer chip had a built-in program that responded to a signal by switching between two available algorithms, then we might “punish” a chip that fails its test when using the default algorithm (due perhaps to a wrong bit somehwhere in its coding) by applying the signal to make it switch to the back-up version. The only “freedom” required of the chip is to perform as programmed when the “switch to backup” signal is applied, and the only “freedom” required of a human (in order to “justify” applying censure or punishment as a tool of control) is to have a built-in propensity for avoiding behaviours that it reasonably expects will lead to censure or punishment.