SUD is a treatable mental disorder that affects a person’s brain and behavior, leading to their inability to control their use of substances like legal or illegal drugs, alcohol, or medications. Symptoms can be moderate to severe, with addiction being the most severe form of SUD.¹ Addiction is a chronic disease characterized by drug seeking and use that is compulsive or difficult to control, despite harmful consequences. The initial decision to take drugs is voluntary for most people, but repeated drug use can lead to brain changes that challenge an addicted person’s self-control and interfere with their ability to resist intense urges to take drugs. These brain changes can be persistent, which is why drug addiction is considered a "relapsing" disease—people in recovery from drug use disorders are at increased risk for returning to drug use even after years of not taking the drug.

Understanding SUD as a treatable medical condition is core to ending stigma, and criminal justice agencies should provide training on the science of addiction to staff members and leaders upon hiring and refresh this training at regular intervals. These trainings may be tailored to the audience in both content and format. For example, law enforcement officers may need training on how to identify a person with an SUD and about connections to treatment available in the community, while a judge may need information about how medication-assisted treatment (MAT) can help a person with SUD and/or how conditions of release can impact treatment and recovery. Similarly, law enforcement officers may respond best to short training videos that can be shown during roll call, while a judge may prefer to read a written report on best practices.