When officers in California suspect you of driving under the influence, they may administer a breath or blood test. These tests determine your blood alcohol content (BAC) level. Each has its good points, but they also both have their flaws. Because of this, neither is infallible in court.
Breath tests are more common. They are both quick to administer and are not invasive. Not only that, but implied consent laws make it so that a driver must take a breath test when asked. If they do not, prosecutors can use this against them.
However, breath tests are not always accurate. Many components can affect a reading. For example, an officer may not have calibrated the device. There may be a defect in the machine itself. A driver can also consume other things that can cause a high BAC level reading, such as cough drops.
Blood tests are more time consuming and invasive. Implied consent laws do not often cover them, so you can refuse to take it. They involve drawing blood to have it tested at a lab for BAC levels. This is one reason they may be more reliable than breath tests. But blood can become contaminated in the lab. Overworked staff can mix up results. A person can also suffer from health conditions that affect results, such as diabetes.
If you are curious and wish to learn more about DUI related crimes, take a look at our linked web page. You can read more about laws in California, discover how the courts handle convictions, and learn more about BAC testing methods.