House Speaker John Boehner is once again talking up a lawsuit against the Obama administration for declining to arrest and deport illegal immigrants who were brought here as children and those who have significant family ties to U.S. citizens.

The Obama administration believes that prosecutorial discretion -- the right of the executive branch to decide which cases to pursue, and which not to pursue -- gives it the necessary authority. House and Senate Republicans vehemently disagree.

Under a House resolution passed last year, the House was empowered to file civil suit against "the President, or any other officer or employee of the United States, (who) establishes or implements a formal or informal policy to refrain from enforcing any provision of federal law in violation of the requirement that the President 'take care that the laws be faithfully executed'."

That's pretty clear, as is the principle behind it:  When there is a clear violation of federal law, the president is required by the Constitution to "take care that the laws be faithfully executed" and prosecute that violation, regardless of whether he finds it popular or convenient.

Principles can be dangerous things, however. If you're going to take a stand on principle, you must take that stand regardless of circumstance or situation. That's the whole idea of a principle. And under the principles as outlined by the House, President Obama is equally required to prosecute President George W. Bush, Vice President Dick Cheney, former Defense Secretary Donald Rumsfeld and whole lot of people at the CIA for torture and conspiracy to torture.

True, as a political matter, some people still choose to quibble about whether U.S. officials engaged in torture. However, as torture is defined in federal law, there is no doubt whatsoever that we have tortured people. That law defines torture as an act "specifically intended to inflict severe physical or mental pain or suffering ... upon another person within his custody or physical control," and there is no serious question about whether such acts occurred. (There's also no "escape clause" in the law about "except in certain circumstances".)

The law is just as clear that "a person who conspires to commit an offense under this section shall be subject to the same penalties" as a person who actually conducted the torture. In other words, if you helped to plan, approve or otherwise assist in torture, you are guilty of torture, punishable by 20 years in prison, life in prison or even death, depending on its scale.

That's the law, plain and simple. If you want to argue that violations of the law must always be prosecuted, then illegal immigrants should be deported and President Bush and a good chunk of his Cabinet should be prosecuted. If you want to argue that illegal immigrants should be deported and President Bush should NOT be prosecuted, then you're not standing on principle. You are picking and choosing which laws to enforce and engaging in allegedly unconstitutional "prosecutorial discretion."

I've long made it clear that I don't believe that torture prosecution is justified. The political turmoil would be too great, and I don't believe it would produce justice. Yes, the law against torture was broken, repeatedly and on a large and organized scale. But we, the people of the United States, all knew it was being broken at the time and we, the people of the United States, tacitly agreed to it. The guilt is a collective guilt that should not be sloughed off onto scapegoats by going back and pretending that tacit acceptance never occurred.

But again, there's a strong parallel with the immigration argument. For close to two decades, under Republican as well as Democratic administrations, we looked the other way while the immigration laws weren't enforced because politically powerful interests wanted the cheap labor those immigrants provided. Despite what the law clearly said, we tacitly agreed to look the other way while that law was broken.

Sure, some protested against that lax enforcement, just as some of us protested lax enforcement of the laws against torture. But in neither case did those protests make much headway. And as with the torture case, it would be unjust to now insist on a literal reading of the law and root out millions of people whom we all but invited here, back when we thought their presence here suited our purposes.

If you disagree with that conclusion, fine. Just don't go hiding that disagreement behind a "principle" unless you are really, honestly prepared to honor that principle in all cases and live with its repercussions. I suspect most are not.