Why the Capitol Riot Inquiries Leave Room for a Broader Commission

Republicans have argued that the existing Justice Department and congressional investigations will address the assault. But they have strict limits.

As the Senate moves this week toward voting on the creation of a 9/11-style commission to investigate the Jan. 6 attack on the Capitol, Republicans have raised a series of arguments against it. They have objected to the inquiry’s scope, its length and even the process for hiring its staff. But last week, announcing that he too would oppose the plan, the Senate minority leader, Mitch McConnell of Kentucky, made another argument: He claimed that the commission was redundant, noting that the Justice Department and congressional committees are already looking into the assault. “It’s not at all clear what new facts or additional investigation yet another commission could lay on top of the existing efforts by law enforcement and Congress,” Mr. McConnell said.