Earlier this month, a group of Democratic senators signed an amicus curae brief in New York State Rifle and Pistol Association v. City of New York, defending New York City's blatant attack on the Second Amendment. For years, those who live in NYC could transport handguns, as long as it was to a few select gun ranges in the area. If you were a gun owner in NYC and wanted to take your firearm outside of city limits to a different gun range, that wasn't allowed.

New York State and City have since changed their statutes and now allow gun owners to transport firearms throughout the city. NYC is now arguing that the Supreme Court does not need to hear the case because it's "moot."

According to the group of Democratic senators, the Supreme Court should turn down the case because it's political in nature. At the end of their letter, the Democratic senators essentially told SCOTUS to dismiss the case or they would move to pack the High Court.

A group of 56 Republican senators, lead by Senate Majority Leader Mitch McConnell (R-KY), sent their own letter to the Supreme Court, urging the justices not to be impacted by Democrats' empty-handed threat.

“The Democrats’ threat to pack the Court if it doesn’t rule the way they want is synonymous in American history with the idea of an unprincipled power grab. Instead of improving their arguments, our colleagues seem determined to undermine our constitutional structure,” McConnell said in a statement. “Senate Republicans reject this dangerous and opportunistic assault on our independent judiciary and will continue to uphold our oath to protect and defend the Constitution of the United States.”

Here's the letter (emphasis mine):

August 29, 2019 The Honorable Scott S. Harris

Clerk

Supreme Court of the United States

Washington, D.C. 20543 Re: New York State Rifle & Pistol Association v. City of New York, No. 18-280 Dear Mr. Harris: We write with regard to the petition in the above-titled case. That petition challenges a New York City law forbidding the transportation of locked, unloaded handguns, with few exceptions, as a violation of the Second Amendment. The City changed its laws after the Court granted the Association’s petition. The Court therefore confronts the question whether the change in New York City’s laws has mooted the Second Amendment challenge. On August 12, several of our Democrat colleagues filed a brief amicus curiae in support of the City urging the Court to dismiss the case as moot under Article III of the Constitution. We of course have no problem with Senators submitting amicus briefs. Many of us have done so. But our colleagues did more than raise legal arguments in favor of mootness. They openly threatened this Court with political retribution if it failed to dismiss the petition as moot. The brief’s final paragraph warned: “The Supreme Court is not well. And the people know it. Perhaps the Court can heal itself before the public demands it be ‘restructured in order to reduce the influence of politics.’ Particularly on the urgent issue of gun control, a nation desperately needs it to heal.” The implication is as plain as day: Dismiss this case, or we’ll pack the Court. There is no greater example of the genius of our Constitution than its creation of an independent judiciary. Alexander Hamilton explained in Federalist No. 78 that “[t]he complete independence of the courts of justice is peculiarly essential in a limited Constitution.” Only an independent judiciary can “guard the Constitution and the rights of individuals from … dangerous innovations in the government, and serious oppressions of the minor party in the community.” And history has proven the wisdom of this design. Time and again, our independent federal courts have protected the constitutional rights of Americans from government overreach even when that overreach was politically popular. But judicial independence is under assault. Democrats in Congress, and on the presidential campaign trail, have peddled plans to pack this Court with more justices in order to further their radical legislative agenda. It’s one thing for politicians to peddle these ideas in Tweets or on the stump. But the Democrats’ amicus brief demonstrates that their court-packing plans are more than mere pandering. They are a direct, immediate threat to the independence of the judiciary and the rights of all Americans. The Association has asked this Court to consider the constitutionality of a law that it believes infringes on the fundamental constitutional rights of ordinary New Yorkers. Democrats have responded by threatening to pack the Court if it decides in favor of the Association. Americans cannot trust that their constitutional rights are secure if they know that Democrats will try to browbeat this Court into ruling against those rights. We are deeply concerned by our colleagues’ amicus brief and the ideas it promotes. We take no position on the underlying Second Amendment question nor on the mootness issue currently before the Court. But judicial independence is not negotiable. We will brook no threats to this fundamental precept of our constitutional structure. We therefore ask that the Justices fulfill their oaths to “faithfully and impartially” follow the law. They should rule in this case only as the law dictates, without regard to the identity of the parties or the politics of the moment. They must not be cowed by the threats of opportunistic politicians. Our constitutional republic depends on an independent judiciary ruling impartially on the basis of what the law says. We ask that the Justices stand firm and do their part to protect our “government of laws, not of men.” For our part, we promise this: While we remain Members of this body, the Democrats’ threat to “restructure[ ]” the Court is an empty one. We share Justice Ginsburg’s view that “nine seems to be a good number.” And it will remain that way as long as we are here.

The Second Amendment Foundation applauded the GOP senators' letter because of the implications associated with the case.

“If the court dismisses this case there is nothing to prevent New York City from re-enacting the statute. In addition, the gun prohibition lobby is rightly concerned that a ruling against New York City could also apply to other states and cities’ infringements on Second Amendment rights," SAF Founder and Executive Vice President Alan Gottlieb said in a statement. “We’re proud of Sen. McConnell and his colleagues. We have never before seen such an outrageous effort by anti-gun extremists on Capitol Hill to subvert the constitutional process."

According to Gottlieb, if the Supreme Court decides not to hear the case, there's nothing from keeping New York City from re-enacting the statute.

"In addition, the gun prohibition lobby is rightly concerned that a ruling against New York City could also apply to other states and cities’ infringements on Second Amendment rights," Gottlieb said.

The Republican Senators were right for writing this letter. The Supreme Court has the ultimate authority when it comes to deciding whether or not a law is constitutional. Threatening the Court with packing is dangerous. It essentially turns the Court into a political institution, similar to Congress, when it's not supposed to be. The Court is supposed to decide laws' constitutionality, not being activist justices.