Site: nolo.com
... Federal law places few limits on employer drug testing:
Although the federal government requires testing ... including transportation, aviation, and
contractors with NASA and the Department of Defense), federal law ... For the most part, state and local
laws dictate whether an employer may test employees for drugs. ... Iowa law doesn’t require drug testing, nor does it encourage
or discourage testing. ... State law
also dictates the procedures for gathering specimens, conducting the tests,
confidentiality ...