Drinking alcohol is legal, but drinking on the job or drinking that impairs your performance can still get you fired. Employers drug test for multiple reasons, which include discouraging employees from on-the-job drinking or coming to work drunk, to comply with the law and to reduce the risks of on-the-job injury. Employers generally set their own policy on when, why and how to test you.

When to Test

Sometimes testing is mandatory under federal or state law. For instance, employees with any job in the aviation, trucking or railroad industries that the Department of Transportation labels "safety sensitive" have to undergo drug and alcohol testing that meets DOT standards. Employers who can set their own rules on testing may schedule tests based on a number of reasons:

• As part of the hiring process.
• After an accident.
• If your supervisor has reasonable suspicions for thinking you drink on the job.
• At random.
• Post-rehabilitation, to confirm you really did get sober.

Your employer's HR department should be able to explain the company's policy.

Methods of Testing

When your employer asks for a urinalysis test, the drug lab then tests your urine for chemical residue left by drugs or alcohol. Urinalysis is commonly used for pre-employment tests and random testing.

Breath-alcohol devices such as the Breathalyzer are actually blood-alcohol tests that measure the alcohol in your breath and calculate the amount in your bloodstream. Employers and police use Breathalyzer tests to measure current levels of intoxication. This is the preferred test if you've been involved in a workplace accident, or for a surprise test based on your supervisor's suspicion that you're drinking on the job.

Companies can also measure your alcohol levels by taking blood samples or a mouth swab. Hair tests can be used to measure drug use, but not alcohol use.

Employee Rights

At time of writing, federal law doesn't place any restrictions on workplace drug or alcohol testing. Some states, however, set limits on what employers can do. For example, some state laws ban random tests except for people in safety-sensitive positions. If you're being tested as part of the hiring process, companies usually have more legal leeway.

Alcoholism, however, is protected as a disability under federal law. While an employer can't fire you for being an alcoholic, he can still require you to meet the same level of performance as other employees. If you're habitually late or make mistakes due to drinking, you can be fired. If you come in late because you're out all night drinking, your employer doesn't have to change your work schedule to accommodate you. However if you need to enter a rehab clinic, you might be entitled to take that time off while keeping your job.