The grand jury deliberating over the fatal shooting of Michael Brown, a black teenager, in August in Ferguson, Missouri, is likely to decide today whether to indict Darren Wilson, the white policeman who killed him. More than two-thirds of Ferguson’s residents are black, whereas the mayor and most policemen are white, an imbalance that has made this poor Midwestern city a fulcrum of racial tension. Weeks of civil unrest followed Mr Brown’s death; there may be more, and worse, trouble if the predominantly white jury comes down against indictment. In anticipation, earlier this week the governor of Missouri declared a state of emergency, which clears the way for the National Guard (army reservists) to intervene. Hands Up United, an activist group, has said that “people around the world” will respond to the grand jury’s decision—which may not be made public until Sunday, to give police time to prepare.