Typical anti-drug stupidity. Note that the article says she PASSED ALL THE MANDATORY DRUG TESTS FOR HER JOB. This proves pretty incontrovertibly that she wasn't "using" as it is virtually impossible to fake such tests (in fact, they are far more likely to yield a "false positive" than a "false negative".
The idea that possession=use is simply bullshit. And in fact, even use should not be a factor in employment--the ONLY criterion should that the person does his/her job the way they are supposed to do it. Making those judgement calls is what managers are supposed to do. "Drug-testing" requirements are simply substituting blanket blind rules for management judgement.
Most mandatory drug tests are pre-hire and post-accident. "Random tests" are expensive, and become lawsuit bait if everyone isn't randomly tested at once. Quite possible to pass the test and be a user, just stay clean before the initial test, and don't get in a wreck.
BTW, most jurisdictions frown on having a drunk behind the wheel, too. (No CDL, No Chauffer's license with DUI). Mere posession of booze is not a crime if you are not a minor(unless you are driving wih an open container in many states). Drugs are a different story.
There are far better test cases, where someone had marijuana growing on some remote corner of a large property, and lost their guns, even though a quite credible case could be made that they were unaware of the presence of the plants.
You want a test case, go there, not flying the flag for folks who knew they were in violation of the law.
I agree in many cases that performance on the job should be the main criterion, but some jobs are considered important enough, or to have a great enough potential for disaster that a condition of employment is not using drugs, or abusing alcohol. Sea Captains, Commercial Truck Drivers (D.O.T.), and Airline Pilots are all examples of occupations in which the standard for intoxication is 0.04% B.A.C., not the 0.08 to 0.10 % for ordinary drivers. We as a culture consider a busload of schoolchildren important enough that we expect a higher standard of behaviour.
Or should we wait for the wreck to decide there might be a problem?