Nearly a year out from the first votes being cast in the Democratic primary contest, we are awash in ideas for reform of the American political system — some of them good, others flatly unrealistic, and at least one of them uniquely terrible.

Abolishing the Electoral College is a very good idea, but it requires the passage of a constitutional amendment, and that's exceedingly unlikely to happen. Also very good and quite a bit easier to achieve would be a push to protect voting rights and make exercising them easier. Eliminating the filibuster in the Senate is another good idea if the Democrats gain a majority, as long as they're willing to live with the consequences the next time they find themselves in the minority. Other structural changes that would enhance Democratic power — giving statehood to the District of Columbia and Puerto Rico; breaking gargantuan California into several smaller states — are fanciful in the current political climate, but there's nothing illegitimate about the effort.

But one proposal stands out as categorically worse than the others and bound to backfire catastrophically. That's the idea of packing the Supreme Court.

Justifiably furious about Senate Majority Leader Mitch McConnell's (R-Ky.) decision to deny even a hearing for Merrick Garland, Barack Obama's choice to succeed conservative justice Antonin Scalia, and terrified of a Supreme Court tilted sharply to the right by President Trump's appointees, Democrats have started to suggest that once they win the presidency and a Senate majority, they will go boldly where Franklin Delano Roosevelt threatened to go in 1937 but ultimately didn't: gaining a liberal majority on the court by increasing the total number of seats and filling them with progressive jurists.

After all, the argument goes, the Constitution doesn't stipulate how many justices should serve on the Supreme Court at any given time. Nine is an arbitrary number. If Republicans could arbitrarily refuse to permit a hearing and an up-or-down vote on Garland, thereby effectively stealing a precious seat on the high court for the right, then why shouldn't the left go one better? Why not add two seats, or four, or six, and make sure to place solid progressives in them? That would teach Republicans a painful lesson, demonstrate the kind of ruthlessness that Democrats so often seem to lack, and give liberals a firm majority in the most divisive cases for the foreseeable future.

Sounds great. Except that this isn't at all what would happen. What would happen — with something close to complete certainty — is this: The next time Republicans took control of the presidency and the Senate, they would immediately expand the court further — by another two seats, or four, or six. Hell, why wouldn't they just double the number of justices? Or triple them? And then the Democrats would do the same yet again after that.

Democratic court packing would ignite a partisan arms race that would quickly culminate in the complete dissolution of the court's authority, with one party adding seats to "win" until the other party gets the chance to do the same by adding still more seats. How long until the number of justices on the Supreme Court surpasses the number of senators? Or House members?

Long before that happened, the institution would be reduced in the eyes of the public to what its most severe critics have long claimed it is: a kind of super-legislature whose extraordinarily powerful members are appointed for life rather than elected by the voters. That the battle for majority control of this unelected legislative body would not be a contest between the appointing parties for a fixed and finite number of seats but a constant expansion of the body's size would only add a layer of absurdity to the spectacle.

All of which means that if the goal is to give the Republicans a taste of their own medicine and enjoy the fruits of ruthless power politics, the court packing gambit would be a complete failure for Democrats. Only if the goal is to shred the legitimacy of the judicial branch of government could it be judged a success.

If Democrats want to teach Republicans a lesson, and open up the possibility of de-escalation of the judicial wars, they could instead refuse ever to confirm Republican appointees to the high court when they have majority control of the Senate. McConnell claimed (unconvincingly) that he was justified in refusing hearings and a vote on Garland because Scalia died less than a year before a presidential election. Democrats could dispense with that flimsy pretext and simply refuse to confirm any justice nominated by the opposing party at any time. That might persuade Republicans that they went too far with Garland. If it doesn't, we would face the prospect of a shrinking court as vacant seats go unfilled whenever the presidency and Senate are held by different parties. That's not good, but it's better than an infinitely expanding court.

If, on the other hand, Democrats are interested in more sweeping institutional changes to the Supreme Court to get us out of the current mess, there are plenty of ideas floating around. The smartest of these would limit terms for the justices to 18 years and regularize appointments by staggering them every two years. Every one-term president would get to make two nominations, and every two-term president would get four. That would do a lot of civic good — by making appointments much less dependent on chance and thus much fairer than they currently are. The result would be a significant lowering of the stakes on both sides.

Court packing moves in the diametrically opposite direction by injecting a highly combustible substance into an already overheated and turbulent political environment. Just by talking about it as a serious proposal, Democratic candidates run the risk of persuading Trump to preemptively pack the court with conservatives ahead of the 2020 election in order to get ahead of the threat. Responsible actors on both sides of the partisan divide need to back away from the suggestion and vow not to pursue it.

Those who refuse will have only themselves to blame if and when the idea ignites a conflagration that leaves their own side badly burned.