Don't see the relevance of "original" English Common Law. Non-competes are a very, very regular/common part of modern business in America.Quote from rwk:
Good catch. The Wikipedia article also says this: . . .an over-broad CNC may prevent an employee from working elsewhere at all. English Common Law originally held any such constraint to be unenforceable as a matter of public policy.
See Mark Hurd of HP, Lee Kai-Fu of Google, for the high-profile examples. It's a part of standard employment contracts for critical employees in many industries.