Come up with a new test that accurately labels someone driving under the influence of marijuana. The urine test doesn't

The current urine test given to people suspected of driving under the influence of marijuana is not an accurate test. The fact that it only detects THC metabolites does not tell when the last time of ingestion took place making the suspected party falsely guilty. One with this knowledge who refuses the test also looks guilty when they actually are trying to avoid self incrimination from an invalid test. Driving under the influence of any chemical is dangerous, but we should have more accurate test if they are used to strip way someone's freedom.