While abuse of all drugs is ever increasing, the abuse of synthetic drugs poses a unique problem. Since these drugs are designed and produced separately, they must each be banned and restricted separately and leads to a very difficult process meaning they stay on the market. The most popular synthetic drugs include cannabinoids that resemble marijuana, bath salts that resemble the effects of cocaine and meth, and painkillers that resemble opioids. The recent death of singer Prince has been linked to overdose of the synthetic opioid fentanyl. Many people develop an addiction to prescription drugs and then turn to fentanyl because it is cheaper, but it has a much higher incidence of abuse and overdose. A federal drug policy adviser supports legislation that would allow prosecutors to use sales strategies as evidence when prosecuting synthetic drug manufacturers.