A more thorough explanation:

A pretextual arrest is when a person is arrested for a minor offense, but the real reason for the arrest is to investigate the person's involvement in a more serious crime for which there are no lawful grounds to make an arrest.

For example, a police officer may pull over a driver for a minor traffic violation, such as a broken taillight, but then arrest the driver for suspicion of drug possession. The real reason for the arrest was not the broken taillight, but the officer's suspicion of drug possession.

This type of arrest is controversial because it can be seen as a violation of a person's rights if there is no probable cause for the arrest. It can also lead to racial profiling and discrimination.