The Green Lantern Theory of Politics is the naive idea that political actors are not truly constrained by other political actors, but in fact can do anything given sufficient willpower. In recent years it has been used mainly to blame President Obama for not forcing Congress to do a broad range of things, when in fact Congress is an independent and co-equal branch of government that the President does not control.

Most of what is being written and said about what the current presidential candidates should do to stop police brutality toward people of color suffers from a related misunderstanding, which to keep with verdant terminology we can call Emerald City Theory. Emerald City Theory holds that all aspects of U.S. policy are controlled from Washington D.C. In L. Frank Baum’s books, the Emerald City was at the center of the Land of Oz. If you had a problem all you had to do is walk the yellow brick road to this seat of power, which oversaw all aspects of life throughout the realm.

In some policy areas, for example those concerning the economy and health care, there is a great deal of truth in Emerald City Theory. But for others, such as education and criminal justice, Washington simply isn’t where most of the action is in our federated system of government.

In the U.S., state and local law enforcement dwarfs that at the federal level, whether one looks at the number of officers, arrests, trials or courts. The FBI for example employs a third fewer people than New York City’s police department. The federal role in incarceration is also a footnote to the huge presence of state and local government.

To ask what Congress should do to stop police brutality, or what Bernie Sanders, Hillary Clinton, Jeb Bush or any other candidate for President will do if elected, is to fall for Emerald City theory. To be sure, residents of the Emerald City can and should acknowledge the pain of the victims, use the bully pulpit to condemn racism, and launch federal investigations where needed. But none of these things will have the impact of even a single large American city’s mayor and police chief deciding to take on the issue.

There is in short no yellow brick road for activists to walk in this case. There are instead hundreds of roads which lead to state capitols, city halls, and county commissions. Like the Wizard of Oz, people in Washington can put on an impressive display but don’t have the power to deliver the changes that the country needs.