drug testing
Blood samples waiting to be processed.
One of the reasons that drug tests are a colossal scam is that not all drugs stay in your system for the same amount of time. In fact, some of the least dangerous drugs such as marijuana can be detected in your urine, blood, and hair for much longer than harder drugs such as heroin and meth — meaning that schools, employers, and law enforcement agencies that drug test disproportionately penalize marijuana users.