Right now the political class is speculating about whether or not Senate Republicans will allow President Obama to place another justice on the Supreme Court. But look out slightly further: Suppose a Democrat wins the presidency, but Republicans manage to hang on to the Senate. Would they agree to confirm any nominee of President Sanders or Clinton? Given their past history of extremist procedural obstruction, I'd say chances are pretty slim.

That pegs the earliest date at which the Supreme Court justice might be confirmed to after the 2018 elections. But wait, Republicans are typically favored in midterm elections, and the 2018 map is strong for them. If Democrats can't do it in 2016, then 2020 is likely the earliest they could retake the Senate. In January 2021, assuming they haven't retired or died, Justice Stephen Breyer will be 83, Justice Anthony Kennedy will be 84, and Justice Ruth Bader Ginsberg will be 87.

It's a grim thought, but glancing over some actuarial tables I'd guess at least one (and probably more than one) of the above justices will no longer be on the court by that time. With Antonin Scalia dead, the remaining eight justices would be evenly split between liberals and conservatives — but of the three oldest listed above, two are liberals and only one conservative. With the Supreme Court little more than a venue for partisan combat, the course of the American state over the next presidential term could very well turn on which of several octogenarians manages to cling to life the longest.

The cracks in the American constitutional order are showing.

As Josh Marshall points out, the last time there was a vacancy on the court that lasted an entire year was 170 years ago. This is because, as liberals were quick to point out, the Constitution says that the president is supposed to appoint people to the Supreme Court, with the Senate's "advice and consent."

And that is very true! For much of American history, the Senate has granted the president a good bit of deference. So long as he put up someone who was decently qualified, he'd get his choice of nominee (with a few exceptions). That worked well for making sure that somebody at least was on the bench making arguments reverse-engineered to support a political conclusion — I mean, divining the original intent of the Founding Fathers.

The structural problems with this 17th-century mechanism are threefold. First, the rate at which Supreme Court justices die or resign is totally arbitrary — in fact, the United States is the only democracy on earth that grants life tenure to justices.

Second, the Senate is a piece of junk. It's violently anti-democratic, and the fact that only one-third of it is ever up for election makes it extremely structurally conservative. If part of Congress must sign off on new justices, it ought to be the House.

Third, and perhaps most importantly, there is no way to resolve disagreement should the Senate simply refuse to confirm anyone. The Constitution just jams the president and the Senate together, and says they have to come to agreement. But what if they simply refuse? If the presidency and the Senate become structurally biased towards opposite parties — a particular concern given that one can hold a majority in the Senate with states which only contain about 18 percent of the population — the country has to wait for demographic trends to take hold, or for a recession to happen during an election year, to push one party out of power.

Now, the more outlandish scenarios outlined above are not that likely. But most people seem basically resigned to Senate conservatives talking themselves into stalling for an entire year so as to have a shot at replacing Scalia with someone comparably reactionary. It's simply ludicrous that the key decisions of a great nation can hinge on something like this (or the Electoral College, or the debt ceiling).

Of course, a big part of why the Constitution is such an anachronistic mess is that it's almost impossible to change. But still, it turns out that there has been some progress in the design of political institutions since the late 1700s. And one of the big no-no's discovered over the years — as evidenced by the fact that every single U.S.-style presidential system outside the U.S. has collapsed — is putting up too many barriers to forward movement. Forcing different branches of government, elected by different populations, does tend to force compromise. But when compromise can't be had, it also makes the system brittle and prone to rupture.

Fingers crossed that we don't have a Bush vs. Gore situation in 2016 with a deadlocked court.