Because of Reapsta's objection, I went back and re-read the OP. Two things stuck out at me. First off, they were citing MADD as the source of these concerns, and that automatically makes the rest of the article highly dubious. Those guys are the kings of misleading people with bogus interpretations. The other thing was how they were spinning it. They were very deliberate in how they described people. Specifically their usage of "has marijuana in their system" when they're referring to the new law, as opposed to being stoned, impaired, under the influence, etc when referring to the old one. Under current law, if a worker shows up smelling of alcohol or marijuana, an employer may remove the employee from a dangerous or sensitive job, such as running medical lab tests in a hospital, or operating heavy equipment. But if Proposition 19 passes, the worker with marijuana in his or her system may not be removed from the job until after an accident occurs. Typical MADD bullshit. Here are the two clauses of the proposed law that are relevant to the concerns that Reapsta shares with them.
(a) This act shall not be construed to affect, limit, or amend any
statute that forbids impairment while engaging in dangerous
activities such as driving, or that penalizes bringing cannabis to a
school enrolling pupils in any grade from kindergarten through 12,
inclusive.
(c) No person shall be punished, fined, discriminated against,
or be denied any right or privilege for lawfully engaging in any
conduct permitted by this act or authorized pursuant to Section
11301. Provided, however, that the existing right of an employer to
address consumption that actually impairs job performance by an
employee shall not be affected.
It seems to me that it's still illegal to operate a forklift or drive the Greyhound bus if you're fucked up, and employers still have the right to prohibit people from working if they're impaired. MADD almost always promotes prohibition first and foremost. Their concern here isn't people driving the bus stoned, but anybody who ever smokes dope driving a bus. That's two very different things.