Currently, the NFL's threshold of THC levels to trigger a positive marijuana test is 15 nanograms per milliliter. The NFL got that number from the World Anti-Doping Agency a few years ago, but WADA raised its level to 150 ng/ml last summer. MLB's threshold is 50 ng/ml.
Source: FOX Sports
So yesterday they released the "Rice" rule on domestic violence and today there is word of an impending "Gordon" rule.