Urine tests for welfare recipients

[Clodfobble]

They've tried. From the ACLU's website on the topic:

The 1996 Welfare Reform Act authorized (but did not require) states to impose mandatory drug testing as a prerequisite to receiving state welfare assistance.

Under the Welfare Reform Act, people convicted of drug offenses are subject to a lifetime ban on receiving cash assistance and food stamps.

Michigan is the first and only state to require random drug testing of all welfare recipients. In its lawsuit fighting the Michigan policy, the ACLU contends that "mandatory drug testing of a broad swath of the adult population has never in our nation's history been proposed or enacted by a state government, much less approved by a court." The Sixth Circuit Court of Appeals upheld the lower court decision striking down Michigan's policy.

Although no other states have implemented a law as extreme as Michigan's, Arizona and Vermont are currently considering similar legislation.

Emphasis mine for clarification, since I took some quotes out of order. There's also more on there about several other states who have considered and rejected mandatory testing, usually in favor of selective testing of just the likelier candidates in order to save money.