Recently, the California Supreme Court held that competent evidence of variations between people's breath alcohol levels and blood alcohol levels is admissible to show that breath tests results can overstate the actual blood alcohol level of a driver in DUI / Drunk Driving prosecutions. This scientific principal is called "partition ratio variation" which has been well documented in the scientific community for decades. This variation is caused by all breath testing machines being programmed to assume everyone has the same variation formula. In reality, this formula is only based on an average and does not take into account an individual's own ratio of breath alcohol levels compared to blood alcohol levels. Looks like credible science is making its way back into California courts.