That is only one of the arguments made by North Dakota and Minnesota two days ago in front of the US Supreme  Court.  

By June 30, 2017, we will know whether that is still the law or not.

Just like gay marriage, firearms rights, and any other laws, the last word from the US Supreme Court is what the law actually is.  

Since  the US Supreme Court is still wrestling with breathalyzer evidence admissability at least 50 years after they became common, your Hound Labs Inc. test is not likely to be useful for marijuana detection, or useful to fire someone, or useful to convict someone of Driving Under the Influence in the immediate future.