A San Diego DUI defense attorney in this video may rebut the official duty presumption generously enjoyed by DMV. The lawyer may be able to demonstrate a Title 17 California Rules of Regulations violation which could be a failure to follow any standard in any respect.
If the attorney does so, the State of California has a burden to show the (breath or blood) test results are (somehow still) reliable (if possible but unlikely) despite the Title 17 violation.
This new San Diego County DUI Law Center California DMV Hearing Officer Manual article quotes DMV's Manual regarding such a critical rebuttal of the issues as well as Attorney Stipulations and Lawyer Objections.
For example, most important California DMV documents are subject to a DUI defense attorney's objection. Section 1280 of California's Evidence Code – Record by Public Employee Exception to the Hearsay Rule - permits admissibility of any such document if these 3 requirements are shown.
The writing was:
a. made by and within the scope of duty of a public employee; AND
b. made at or near the time of the act, condition, or event; AND
c. the source of information and method and time of preparation were such as to
indicate its trustworthiness.