Tweet of the Day: Kill Your Rituals, Not Your Darlings
Jurisdiction Friction is one of the staples of crime dramas and government thrillers. The concept is simple, whenever two (or more) police forces, investigative services, or intelligence branches investigate the same (or related) case, each side will claim jurisdiction over the case, either forcing the other out or taking control of the case. In real life rules of jurisdiction are designed to avoid such clashes, although the do occur. This is the reason why in the U.S. (and in other countries) federal police forces form task forces with local police: the feds bring in the resources while the local have knowledge of the lay of the land.
For the author it serves one of two functions: it creates conflict between the good guys or allows the introduction of a bad guy with a badge. The first usually gets resolved when both sides understand they have more to gain from working together than working against each other. The second can either be a individual who abuses their power for petty personal reasons or an entire branch of government that is running a major conspiracy the protagonist must expose/destroy/survive.