The employer in this case is a government institution, and thus is restricted by the same bonds that chain the government as a whole.
I've found it pointless to argue with a drug warrior. In their minds, there is a whole set of footnotes written in invisible ink on the Bill of Rights that say "unless you are trying to prevent someone from using drugs."
Wow, you seem to have an unending supply of trite soundbite bullcrap.
So? Random drug tests required by government agencies and schools are clearly constitutional (besides being extremely useful), and courts have almost invariably upheld them. Such was the case here. If some ACLU type had managed to get a background check policy struck down, and Mister Kindly with the "loving touch" was a pedophile rather than a potential pothead, folks on this forum would be the first ones to squeal. If you won't do what your employer legally wants you to do, it's twenty-three skidoo, Gramps!
Yeah, but he consented.