On February 13, the very day of Justice Antonin Scalia's untimely death, Senate Majority Leader Mitch McConnell stunningly announced that the Senate, under Republican control, would not consider any nominee President Barack Obama put forth to succeed Justice Scalia. McConnell and his fellow Senate Republicans insisted that the American people should have the opportunity to weigh-in on this issue, and that it was therefore President Obama's successor, rather than President Obama, who should have the authority to replace Justice Scalia.

Despite that unprecedented proclamation, on March 16 President Obama nominated Merrick Garland, the Chief Judge of the United States Court of Appeals for the District of Columbia, to succeed Justice Scalia. Although everyone with even a modicum of expertise agrees that Chief Judge Garland is a highly-qualified, highly-respected, and moderate nominee, Senate Republicans have adamantly refused even to consider his nomination.

The purported "justification" for the Senate Republicans' refusal to even consider Merrick Garland's nomination is that the next president should be the one given the authority to appoint Justice Scalia's successor. By employing this strategy, Senate Republicans, praying for a victory in November, hope to enable Donald Trump, rather than Barack Obama, to appoint the next Justice of the Supreme Court.

In a new scholarly article, law professors Robin Kar and Jason Mazzone have taken a deep dive into the history of Supreme Court nominations to test the plausibility of the Senate Republicans' purported "justification" for their action. Not surprisingly, they find that the Senate Republicans' alleged "justification" is completely bogus. It is, in short, exactly what it appears to be -- a cynical and unconscionable sham.

What Kar and Mazzone found is that over the entire course of American history there have been 103 instances (prior to this one) in which an elected president faced a vacancy on the Supreme Court prior to the election of the next president. They found that in every one of those 103 instances, the president nominated and, with the advice and consent of the Senate, appointed the new Justice. There has not been a single exception to this practice in all of American history. And this is true even when, as in the current situation, the vacancy arose during an election year. In short, this would be the first time in American history that a president in President Obama's position would be denied the opportunity to fill a vacancy on the Supreme Court.

As Kar and Mazzone note, there have been six instances, all in the nineteenth century, in which a sitting president failed to secure the confirmation of a nominee before his term ended. But those six cases were clearly distinguishable from the current situation.

In three of those cases -- all of which occurred more than 150 years ago - the nomination was made by a president who had not been elected president. They all involved situations in which a vice-president had assumed the presidency after the death of the president. At that time, early in our nation's history, it was assumed that unelected presidents did not enjoy the full powers and authority of elected presidents.

In the three other cases, all of which also occurred in the 19th century, the nomination of a new Supreme Court Justice was made after the election of the president's successor. In those situations, it was thought reasonable to permit the already elected successor to make the nomination.

The bottom line, then, is this: In 225 years of American history, the only times a sitting president has not succeeded in filling a Supreme Court vacancy involved highly unusual circumstances not in any way implicated in the current situation. More to the point, in every one of the 103 instances that mirror the current state of affairs, the president has been able to appoint a Justice to fill a vacancy on the Supreme Court -- without a single exception.

What this clearly demonstrates is that the rationale the Senate Republicans have cynically put forth to "justify" their behavior is in direct defiance of 225 years of American history. The plain and simple fact is that there is no constitutionally legitimate justification for the Senate Republicans' position. It is unprincipled, unprecedented, and, as Kar and Mazzone observe, dangerously destructive to a well-settled Supreme Court confirmation process that has served our nation well from the very founding of the Republic.

Moreover, as Kar and Mazzone warn, such an unprincipled departure from the settled constitutional process will seriously undermine the fundamental "norms of cooperation" that have enabled the Supreme Court appointments process to function reasonably smoothly throughout our nation's history.

The precedent set by this behavior, they conclude, will inevitably lead to a more "politicized appointment process and, ultimately, to a more politicized Court." Having opened the door to such abuse of the confirmation process, the Senate Republicans have now invited similar abuse in the future. None of this bodes well for our nation. It is, truly, unconscionable.