The main principle behind the state's right to ask for a chemical test to determine your blood alcohol level is the implied consent law. It states that anyone with a driver's license automatically consents to testing. No one has the absolute right to operate a vehicle. Every state has an implied consent law. Supreme Court rulings have decided that police may forcibly take your blood in order to test your blood alcohol levels, though on a practical level, that rarely happens. Most states rely on statutes that make refusing to test even more punishing than taking the test and failing. In California, you make a choice between the type of test you wish to take.  If the facility only has blood testing, then you must use that type of test. The information contained in this message is general and should not substitute for the advice and counsel of a licensed attorney.