While the evidentiary threshold is low, grand juries still serve as a check on prosecutorial power. An old saying holds that prosecutors are in such complete control of grand jurors that they could get them to indict a ham sandwich if they wanted. But recent events in Washington and Los Angeles have proved that isn’t always true. Something similar took place in Los Angeles this summer as grand jurors declined to approve indictments against several people arrested during protests against local immigration raids. Many of the defendants had, like those in Washington, been accused of assaulting the authorities.