My friend smoked pot 36 hrs before his drug test. will he fail his test?

It depends but...: Some marijuana (thc) metabolites have an elimination half-life of 20 hours. At 20 hours 1/2 of the ingested drug is gone "eliminated". However, some are stored in body fat and have a elimination half-life of 10 to 13 days. Most researchers agree that urine tests for marijuana can detect the presence of the drug in the body for up to 13 days.