Canadian employers are in a new era of comprehensive risk assessment and risk management. As occupational health and safety issues are becoming top priorities for employers, mandatory drug and alcohol testing programs are increasingly becoming topics of controversy among the courts. Key case laws addressing drug and alcohol testing in the workplace include the following four decisions ( Entrop, Milazzo,Meiorin and Chiasson). These cases are providing guidance for employers on the rights and obligations that come with such testing and help distinguish the different types of substance testing and the implications of each. Some of the key principles that employers are advised to consider before implementing a drug and alcohol testing policy include the following: the need for testing, disclosure, comprehensive policy, probationary periods, and withdrawal of employment offers.