Why hasn't the Supreme Court found the Hatch Act unconstitutional?
The Hatch Act is a law that was passed in 1939. It says that Cabinet employees as well as other non-presidential Executive Branch members cannot talk about candidate-specific issues among other things.
This seems like a clear violation of the First Amendment. But the Supreme Court disagrees with me, since that argument has been presented to it. Why hasn't the Hatch Act been determined to violate the First Amendment when it seems to clearly restrict speech?
Note: I looked up the law's constitutionality. The court's majority opinion was basically "it does not interfere with voting rights so it's OK."