Sounds like a great way to save money and encourage sobriety. Except, to be eligible for unployment, you must first have permanent employment before you can qualify to get benefits when you lose it. Chances are that you're not abusing drugs since many employers require testing and some periodically. So the effort is likely to come up dry. It would likely generate significant cost with little return. Finally, unployment benefits end enforcing a natural limit to how long anyone could enjoy a "free high". Now if you want to actually accomplish something meaningful, test welfare recipients.