If you smoke marijuana in a State where it is legal, it does not matter in Ohio that you smoked it where it was legal, even with a prescription. You can still get an OVI several weeks later. Anything greater than 35 nanograms of metabolite per mL of urine, or 50 nanograms per mL of blood is considered under the influence. This is an exceedingly small amount. Right after ingesting marijuana, your level can exceed 300 nanograms per mL. I represented a client in Delaware, Ohio who failed a urine test almost three weeks after smoking marijuana. If you fall into this category, I recommend you challenge the suggestion you were impaired weeks later and seek an attorney to defend you.