The Metro-Dade Internal Affairs Division, or IAD, is a group of policemen specifically assigned to handle internal security; investigating allegations of wrongdoing by Metro-Dade officers, such as, but not limited to, police brutality, bribery, embezzlement of police funds (such as buy money), the lawfulness of any fatal actions, and other illegalities within the department.
Owing to their job investigating fellow police staff, IAD are often hated by other law enforcement divisions and viewed as 'traitors', and as such IAD officers can usually expect to be treated with suspicion and contempt. Their portrayal in fictional media is often scripted to emphasise this traitorous characterisation, with Internal Affairs agents appearing bullish, uncooperative, devious and devoid of compassion.
- Between them, Crockett and Tubbs were investigated a total of ten times by IAD during the course of the show (and exonerated in each case). According to Tubbs, they came under scrutiny from Internal Affairs so many times that the Division must have had "a permanent poker with our names stenciled on it".