This Thanksgiving, we can still be thankful that we live in a constitutional republic, where laws are made by the people’s representatives in Congress, applied by the courts, and faithfully executed by a president. But I am very worried that our country is on a path toward a future in which, not too long from now, that will no longer be true.

In an earlier age, it was common to speak of the American “experiment” in self-government, because serious observers doubted whether any large country could be ruled successfully by a constitutional republic, rather than by a dictator, king or emperor. After two and a quarter centuries, we have grown complacent.

Because we no longer really worry about the preservation of constitutional government, we have allowed our constitutional system to decay. Activists and scholars have been complaining about the “Imperial Presidency” since at least the Nixon administration, when the historian Arthur Schlesinger Jr. published his now-classic book on the topic.

The trend he observed then has continued apace: Each president tends to exercise more discretionary power, over a wider range of issues, than the previous president; as the president’s power grows, the powers of Congress are diminished.

That many not seem like a terrible thing: the president is elected, in a national election, whereas the Congress is elected piecemeal, according to a plan of representation that no longer seems legitimate to many people, who no longer see the point of giving small states equal representation with large states in the Senate.

There are, however, grave dangers inherent in executive power, which is why the Constitution made sure to assign primacy to the Congress, rather than the president

Powers used to benefit the people can easily be turned to harm the citizens. It is not much of a stretch to believe that any president who succeeds in ignoring the Congress will find it easy to ignore the courts and the Constitution as well.

Against this background, consider the implications of President Obama’s executive order granting temporary protection to an estimated five million people now illegally in the United States.

He had apparently been considering a measure of this sort for some time, and during that time, he often fielded questions about whether he would take such a step. For a long time, he gave answers more or less consistently with what he said on Feb. 14, 2013: “I’m the president of the United States. I’m not the emperor of the United States. My job is to execute laws that are passed, and Congress right now has not changed what I consider to be a broken immigration system.”

Sometimes he said he wasn’t the “king”, and other times, that he wasn’t a “dictator” — but this was Obama’s consistent message: he objected to the immigration laws we have, said our policy to be “broken,” but insisted that, as president, he had to follow the laws.

This month, however, he repudiated that analysis. He declared that because Congress has not passed a new immigration law more to his liking than the status quo, he can decline to enforce large swaths of immigration laws that he regards as “broken.”

To be sure, the White House managed to get a legal opinion justifying the president’s actions, and its argument has some superficial plausibility — just enough plausibility that the president’s partisan friends will be able to forget or ignore that Obama himself had repeatedly insisted that the very steps he ultimately decided to take were unconstitutional.

The folks at Saturday Night Live, however, were not fooled, and their parody of the old Schoolhouse Rock number on how a bill becomes a law, portrayed his action and his executive order as schoolyard bullies, running roughshod over the normal procedures of constitutional government.

I realize that my complaints on this score are naturally suspect: I am a Republican and so can be expected not to like anything this president does.

But partisan Democrats should bear in mind that someday we will have another Republican president, and, for that president, every power this president wields will be a power for that president, too. And, worse, every power this president wields will be the starting-point of some legal opinion justifying something this president hasn’t even contemplated.

And the more partisan Democrats defend this president, the more partisan Republicans are likely to defend some future Republican abuser of executive power. And down that road indeed lies the end of constitutional government in America.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.