This Practice Note explains the offence of driving or being in charge of a motor vehicle with concentrations of specific controlled drugs in excess of specified levels under section 5A of the Road Traffic Act 1988. This offence was created by the Crime and Courts Act 2013 and came into force on 2 March 2015. This Practice Note explains the elements of the offence, the testing for controlled drugs, the available defences and the sentencing of this offence.