The Centers for Disease Control and Prevention’s latest set of guidelines for opioid-prescribing doctors discourages drug testing patients for THC — the psychoactive compound found in marijuana.

A group of Maryland doctors plans to open a medical marijuana testing facility in Columbia to ensure product quality as the state prepares to launch its burgeoning therapeutic cannabis industry.

Do you get high? Do you drive? This is why you need to understand the laws behind DUI marijuana charges — and the particular science of THC, too.