11-COOH-THC is formed in the body by
oxidation of the active metabolite
11-hydroxy-THC (11-OH-THC) by liver enzymes. It is then metabolized further by conjugation with
glucuronide, forming a water-soluble congener which can be more easily excreted by the body. 11-COOH-THC has a long half-life in the body of up to several days (or even weeks in very heavy users), making it the main metabolite tested for
blood or urine testing for cannabis use. More selective tests are able to distinguish between 11-OH-THC and 11-COOH-THC, which can help determine how recently cannabis was consumed; if only 11-COOH-THC is present then cannabis was used some time ago and any impairment in cognitive ability or motor function will have dissipated, whereas if both 11-OH-THC and 11-COOH-THC are present then cannabis was consumed more recently and motor impairment may still be present. Recent studies highlight that individual factors such as metabolism, body fat percentage, and frequency of use significantly impact the detection window of 11-COOH-THC in drug testing. On the other hand, in jurisdictions where cannabis is completely illegal, any detectable levels of 11-COOH-THC may be deemed to constitute driving while intoxicated, even though this approach has been criticized as tantamount to prohibition of "driving whilst being a recent user of cannabis" regardless of the presence or absence of any actual impairment that might impact driving performance. ==Effects==