Abraham Lincoln, whose 200th birthday will be celebrated this day by the 44th president of the United States, served only two years in federal elected office before assuming the presidency in 1861.

Barack Obama, an only slightly more experienced federal legislator at the moment of his presidential ascension, will of course devote most of his attention to Lincoln’s presidential tenure.

But Obama would do well to spare a moment for pondering, and honoring, Lincoln’s term as a member of the U.S. House.

It was as a congressman from Illinois, serving from 1847 to 1849, that Lincoln distinguished himself as a daring critic of executive excess, who believed it was not merely appropriate but necessary for members of the House and Senate to challenge presidents in times of war. Lincoln was so radical when it came to constitutional questions that his stances may well have cost him the congressional career he had hoped to enjoy. But that radicalism has stood the test of time, and it is today one of the facets of the multi-faceted Lincoln that is most worthy of commendation.

Lincoln the congressman stood for the Constitution and against the illicit war-making of an authoritarian president, the atrocious James K. Polk, who ordered the invasion and occupation of Mexican lands with the purpose of annexing new states where slavery would be permitted. Along with his fellow dissenter, John Quincy Adams, Lincoln sought to censure Polk, and daily decried the president’s imperial reach and pro-slavery machinations.

Lincoln’s boldness – he effectively and repeatedly tagged Polk as a liar who had concocted a war based on false premises – set the standard for legislators who perceive a president to be assaulting the rule of law and the better angels of our nature.

When his law partner William Herndon complained that Lincoln’s condemnations of the president were inappropriate in a time of war, the congressman replied in a February 18, 1848, letter that remains one of the great documents of the struggle to maintain constitutional governance:

ON THE MEXICAN WAR

TO WILLIAM H. HERNDON.

WASHINGTON, February 15, 1848.

DEAR WILLIAM: Your letter of the 29th January was received last night. Being exclusively a constitutional argument, I wish to submit some reflections upon it in the same spirit of kindness that I know actuates you. Let me first state what I understand to be your position. It is that if it shall become necessary to repel invasion, the President may, without violation of the Constitution, cross the line and invade the territory of another country, and that whether such necessity exists in any given case the President is the sole judge.

Before going further consider well whether this is or is not your position. If it is, it is a position that neither the President himself, nor any friend of his, so far as I know, has ever taken. Their only positions are–first, that the soil was ours when the hostilities commenced; and second, that whether it was rightfully ours or not, Congress had annexed it, and the President for that reason was bound to defend it; both of which are as clearly proved to be false in fact as you can prove that your house is mine. The soil was not ours, and Congress did not annex or attempt to annex it. But to return to your position. Allow the President to invade a neighboring nation whenever he shall deem it necessary to repel an invasion, and you allow him to do so whenever he may choose to say he deems it necessary for such purpose, and you allow him to make war at pleasure. Study to see if you can fix any limit to his power in this respect, after having given him so much as you propose. If to-day he should choose to say he thinks it necessary to invade Canada to prevent the British from invading us, how could you stop him? You may say to him,–“I see no probability of the British invading us”; but he will say to you, “Be silent: I see it, if you don’t.”

The provision of the Constitution giving the war making power to Congress was dictated, as I understand it, by the following reasons: kings had always been involving and impoverishing their people in wars, pretending generally, if not always, that the good of the people was the object. This our convention understood to be the most oppressive of all kingly oppressions, and they resolved to so frame the Constitution that no one man should hold the power of bringing this oppression upon us. But your view destroys the whole matter, and places our President where kings have always stood. Write soon again.

Yours truly,

A. LINCOLN

Unfortunately, for Lincoln and for America, the congressional champion of checks and balances undermined and disregarded those very checks and balances as the nation’s 16th president.

Lincoln was a strong executive who used all the powers of his position — and a few that had not been accorded it by the framers of the Constitution — to advance the Union’s cause in a time of dramatic internal conflict.

Civil wars test counties and their leaders in unique ways. And Lincoln failed some of the tests, disregarding civil liberties with heavy-handed moves to suspend the writ of habeas corpus in the first year of the Civil War, imposing martial law in border areas, curbing freedom of speech and freedom of the press, disregarding the Congress and ignoring a Supreme Court ruling that sought to rein him in.

As we celebrate Lincoln’s remarkable accomplishments — beginning with the issuance of the Emancipation Proclamation that addressed the original sin of the American experiment — it is well to hail a man and a presidency that served the republic so ably and honorably.

It is well, also, to recognize that even able and honorable leaders misunderstand and misuse their powers, upsetting a necessary constitutional framework and leading by decree because it is easier to do so. In times of national emergency, the proper balances are more difficulty to achieve, and this is Lincoln’s excuse, if not his complete absolution — as even he admitted.

But on this day of honoring the memory of our 16th president for his service to the republic, we should also hail Lincoln’s service to the Constitution as a dissident congressman

Indeed, many comparisons are made between Abraham Lincoln and Barack Obama — both men of humble means, both transplanted Illinoisans, both legislators, both great orators, both lawyers familiar with the Constitution who defended the document in times of national turmoil.

Just as Lincoln opposed the Mexican war of the 1840s, so Obama opposed the Iraq war of the current decade.

Just as Lincoln defended the Constitution against Polk’s abuses, Obama defended it against the abuses of George Bush.

Now, like Lincoln, Obama has assumed the presidency.

There are so many ways in which Obama can and should emulate his worthy predecessor’s presidency. But the current commander-in-chief should emulate Lincoln the wise congressman when it comes to matters constitutional, not Lincoln the overreaching president.