The fatal shooting of unarmed teenager Trayvon Martin in Florida last month would not have captured the media attention it did if the police had done their job. The police did not make an arrest. After conducting a cursory, good old boy investigation, local police and prosecutors summarily declared the killing of Treyvon Marin — who had no motive, no criminal history, and no weapon — self-defense and closed the case.

Authorities in Sanford, Florida initially said that they were constrained by the Stand Your Ground Law. The Stand Your Ground Law makes it easier for civilians who kill other people to claim self-defense. The act was passed in Florida in 2005 at the urging of the NRA and it is difficult for me to ignore the historical context of lynching in the last century.

But the Stand Your Ground Law did not require Florida prosecutors not to press charges. It states that those who claim self-defense are entitled to immunity from prosecution if and only if self defense was justifiable. It is up to police and prosecutors who “use standard procedures for investigating the use of force” to make a knowing and independent determination. (Florida Crimes Code 776.013, 776.032.) Nothing required cops to abdicate authority and pretend that every suspect who claims the dead guy attacked them should go free.

The indifferent response by local authorities to the shooting of a young black man by a neighborhood watchman because he looked out of place is more cultural or institutional, than legal. That is why people from around the country are hoping that a full investigation is done. That is why we are grateful that the federal and state departments of justice are trying to get to the bottom of why George Zimmerman fired his gun at a black teenager coming home from a trip to the store to buy ice tea and Skittles.