It's a nightmare scenario, especially for people who drive commercially for a living. You get pulled over by the police, who administer a field sobriety test. Basic health issues, ranging from diabetes to anxiety or even a bad knee, could result in an officer suspecting you're under the influence. In that scenario, the next step usually involves the officer performing a chemical test, such as a breath test, to determine alcohol impairment. In some scenarios, officers may collect blood, saliva or urine for testing. Some people might consider refusing to allow the officer to perform a chemical test. Doing so, however, has serious implications for your legal situation.