I found this argument from Walter Russell Mead about what happens after the Drug War ends pretty amusing:
Any change in drug policy is likely to disappoint the Stoner Lobby; the decriminalization of drugs is almost certain to lead to tougher non-criminal sanctions against their use. Marijuana may well get a pass, but other drugs will not. If criminal sanctions disappear, drug tests are likely to proliferate. You won’t be able to work in health care or any of the professions if you test positive for most drugs; likely you won’t be able to enroll in many colleges, receive government benefits (including financial aid) or teach.
Any new policy on drugs is likely to be a bit like shifting immigration control from the borders to the workplace. Rather than building high walls along the borders, the Obama administration wants to attack illegal immigration on the demand side: by preventing employers from hiring illegals and punishing them if they fail to get adequate documents for their employees. Modified drug laws might work that way: while the sale and use of drugs might be legal, employers would have the right and in many cases the obligation to monitor their employees and fire those who fail drug tests. Otherwise they would be exposed to massive lawsuits for negligence (you let a crack addict manage my portfolio/treat my cancer/teach my kid), or face government sanctions. Basically, the country would take the position drug use is tolerated but not accepted: that you cannot attend a college, hold a good job, work for the government in any capacity or hold public office if you test positive for certain drugs. I would not be surprised to find politicians pushing to extend the reach of mandatory testing. If athletes must pass drug tests, perhaps actors should have to pass them as well — and a positive drug test would void an employment contract.
I don't think all of this is totally far fetched, but I'm guessing Mead hasn't tried to get a minimum wage job in the past 20 years or so. Lots of those jobs require drug tests already. Higher end jobs outside of government most likely won't, and the idea that they'll start testing you for drugs during college admission is laughable. Elite private colleges already exist as de-facto decriminalized drug zones. Yale and Harvard aren't going to start purging their legacies because Junior or Muffy likes to do a little coke now and then. There's just no way America's economic elites are going to allow themselves to be subjected to the regular, ritual humiliation that is already part of life for many people seeking low wage jobs. Such violations of dignity are for the little people. Just as the War on Drugs is mostly a war on the poor, whatever non-criminal sanctions follow in its wake are likely to be equally focused.