[discostu]

Those detect metabolites, not really good for showing you’re under the influence right then. No good for DUI.

[zipper]

A mass spectrometry positives could provide probable cause for a blood test.

And when coupled with a fingerprint, the chain-of-custody argument is moot.

https://www.inquisitr.com/2091712/all-new-drugs-test-can-detect-cocaine-users-from-their-fingerprints/