If you are stopped under the suspicion of DUI, or were involved in an accident (even if it wasn't your fault) and the officer reasonably suspects you were under the influence of prescription or illegal drugs, you can be forced to submit to a blood test. If you refuse or resist, they will still draw your blood. Based on the refusal alone you face the probability of losing your license for one year regardless of the results of the test. California's "implied consent" law requires any driver to submit to a blood or breath test for alcohol and/or drugs if the officer has a reasonable belief that you are driving under the influence. If you attempt to refuse during this process, the officer is required to read you your "refusal admonition" and follow a specific procedure. Your responses will be noted and will be used against you in court, and at your DMV hearing. Any refusal can result in the loss of your driving license for a year, and possibly increase the penalties you face on a DUI.