Physician assistants have their own licenses with distinct scope of practice. Each of the 50 states has different laws regarding the prescription of medications by PAs and the licensing authority granted to each category within that particular state through the Drug Enforcement Administration (DEA). PAs although trained to prescribe, in Kentucky, Puerto Rico and the US Virgin Islands are not allowed to prescribe any controlled substances. Several other states place a limit on the type of controlled substance or the quantity that can be prescribed, dispensed, or administered by a PA.