Now there is a new study that adds to the evidence that a THC blood levels is not a good predictor of driving performance.

The study published in the journal Clinical Chemistry investigated the connection between THC blood levels and performance in a driving simulator. Even though THC blood levels of participants were often above some states’ “per se” or zero-tolerance limits, driving performance was no worse than those with blood levels below those limits. This suggests current THC per se driving laws may not accurately reflect actual driving impairment in frequent cannabis users.

The best way to find key information is in the certificate of analysis (COA). Some states require COAs to be made available to the consumer, either with paper copies on file in the dispensary, or electronically via QR code on the product.