If one is going to argue a point on principle, then fairness dictates that the principle must stand no matter whose policy is the subject of the discussion of the moment.

With that, I have to declare that my vigorous opposition to Senate Majority Leader Mitch McConnell’s decision to play politics with President Obama’s authority to appoint a Supreme Court justice compels me to make a declaration that is going to anger some readers of this blog.

It is that Donald Trump deserves to be treated fairly if the time comes for him to make a SCOTUS nomination during the heat of a presidential campaign.

I heard the news about Justice Ruth Bader Ginsburg’s hospitalization over a fever and thought what many of you thought as well: What if she can no longer serve on the nation’s highest court? I hate harboring macabre thoughts, but realism requires us to recognize that the justice is 86 years of age and has been battling cancer.

OK, that said, she also is a noted progressive jurist appointed to the high court in 1993 by President Clinton. She is the second-most senior tenured justice on the court, behind archconservative Justice Clarence Thomas, appointed in 1991 by President George H.W. Bush.

The politics gets stickier than pine bar on a baseball bat.

Conservative icon Antonin Scalia died suddenly in early 2016. President Obama wanted to nominate Merrick Garland to succeed him. Garland is known as a judicial moderate who tilts a bit to the left. McConnell intervened. He said under no circumstances should Obama, a lame duck, should be allowed to fill that vacancy. He blocked Obama’s choice in the Senate, which has confirmation power.

Many of us went ballistic. I was one of millions of Americans who were enraged at McConnell’s power play. How dare he interfere with the president’s constitutionally granted authority? He wanted to wait for the 2016 election to play out before handing the matter over to the next president. It was a raw partisan act and it was wrong.

I argued the point on the principle of presidential authority taking precedence.

So, here we are today.

Another president is in office. Donald Trump has selected two high court justices already. If he gets a chance to select a third one in the event that Justice Ginsburg retires or … well, you know … then he gets to nominate a justice to succeed this progressive icon.

We all know what the reaction will be. It will mirror the reaction that erupted in progressive circles when Scalia died and Garland got the nomination. Only this time conservatives will argue that the president deserves to have his nominee seated; progressives will seek to block it, perhaps in the manner that McConnell did.

It would be as wrong to block Trump as it was to block Obama.

The more reasonable — and principled — option would be for Democrats to regain control of the Senate after the 2020 election. Then the Senate could exercise its appointment power when a conservative justice’s spot on the court is vacated. Voters also can kick Trump out of office, presuming he survives the pending impeachment and Senate trial, and elect someone who will forgo the ultra-right-wing agenda favored by the incumbent.

Given my own often-stated bias, I take no pleasure in making this declaration. I feel I must … in the name of principle.

In the meantime, I intend to pray real hard for Justice Ginsburg’s good health.