In the state of California, it is against the law to have a BAC over the .08% limit while driving, not at the time the chemical test is given. Studies have shown that it can take the human body anywhere between 30 minutes and 3 hours for the alcohol to be absorbed. It is conceivable that an individual's BAC could rise after he was stopped and arrested.
The time elapsed between when the suspect is arrested and when the chemical test is administered is approximately an hour. The test could show a level of .10% but because the alcohol was being absorbed, it could have been .07% while the suspect was driving. The suspects' true BAC while driving was within the legal limits even though the test results showed an illegal level.