The need to reverse the slide in presidential authority would perhaps be less urgent if Congress were actually doing anything. But the last two Congresses have passed fewer than 300 laws each, the fewest in modern history. By comparison, the famous “do-nothing” Congress of 1947-48 passed 906 laws.

I saw the problem firsthand when I served in the Treasury early in the Obama administration. Mr. Obama was able to inject about $80 billion into the automobile industry without congressional approval because, in a panicked moment in the fall of 2008, Congress had given George W. Bush’s administration a $700 billion virtually discretionary rescue fund. But when it came to similar challenges — such as reforming the insolvent housing finance giants Fannie Mae and Freddie Mac — the administration was powerless. Today, more than six years after the Bush administration correctly put them into “temporary” conservatorship, they sit exactly as they did in 2008, as if preserved in amber.

The assault on presidential authority dates from at least the early 1970s, when a mix of the Vietnam War, Watergate and a mushrooming executive branch raised fears of an “Imperial Presidency,” as the historian Arthur M. Schlesinger Jr. titled his influential 1973 book.