Over the past 10 years, the backlog in America’s immigration courts has nearly quadrupled to roughly 700,000 cases. On Thursday, Attorney General Jeff Sessions issued a decision that could dramatically expand that backlog at a time when immigrants often wait years before judges decide whether they can remain in the United States. Using his control over the immigration court system, which is part of the Justice Department, Sessions revoked immigration judges’ broad authority to close cases through a process known as administrative closure.