President Barack Obama will order immigration officers to deport “felons not families” as he wields executive power to shield five million illegal immigrants in the most sweeping overhaul of the immigration system in decades.

A 33-page Justice Department legal opinion made public just hours before Obama spoke concluded that he doesn’t have the legal authority to offer broad deportation relief to parents of so-called Dreamers—people who came to the U.S. illegally as children and won a reprieve from deportation in a program known as DACA that Obama created in 2012.”As it has been described to us, the proposed deferred action program for parents of DACA recipients would not be a permissible exercise of enforcement discretion,” Justice Department attorney  Karl Thompson wrote in the Office of Legal Counsel opinion.

The opinion also reveals, in a footnote, that Justice Department lawyers informally raised concerns about Obama’s initial 2012 DACA program before it was enacted.

Senator Angus King, an independent who aligns himself with Democrats, said McDonough was peppered with many questions about the president’s new immigration policy.

“I’d say people stated their views strongly, but I wouldn’t call it contentious. Nobody threw anything,” King told reporters.

Some Democratic senators representing conservative states have expressed concerns over Obama’s timing for this action.

Prosecutorial discretion means you are not required to prosecute every crime — which, since doing so would be impossible, is just a nod to reality. It does not mean that those crimes the executive chooses not to enforce are now no longer crimes. Prosecutorial discretion has never meant that the passive act of non-enforcement has the legal effect of repealing criminal laws enacted by Congress. And it has never even been suggested, because to do so would be absurd, that under the doctrine of prosecutorial discretion, the executive decision not to prosecute certain crimes means the people who commit those crimes should be rewarded for committing them. That, of course, would only encourage others to commit them on a more massive scale.

Yet that is President Obama’s theory. He is claiming not only the power to determine what immigration laws get enforced and which illegal immigrants get prosecuted — power he unquestionably has. He also claims the power to declare (a) that criminal acts are somehow lawful — that illegal aliens now have a right to be here — just because Obama has chosen not to prosecute them; and (b) that those who engage in this unprosecuted activity will be rewarded with benefits (lawful presence, relief from deportation, work permits, etc.), as if their illegal acts were valuable community service.

Today is an important step toward rational and humane enforcement of immigration law. On behalf of America’s workers, we applaud the Administration’s willingness to act.  We have been calling upon the White House to halt unnecessary deportations since Spring 2013 because our broken immigration system is an invitation for employer manipulation and abuse, and U.S.-born workers as well as immigrant workers are paying the price.

By extending relief and work authorization to an estimated 4 million people, the Obama Administration will help prevent unscrupulous employers from using unprotected workers to drive down wages and conditions for all workers in our country.  Although this fix will be temporary, it will allow millions of people to live and work without fear, and afford them the status to assert their rights on the job.

Senate Majority Leader Harry Reid yesterday praised President Barack Obama’s pending immigration plan with warm language: “This is personal to me,” he said. …

The greatest threat to Reid’s re-election is Nevada Governor Brian Sandoval, a Hispanic Republican who defeated Reid’s son, Rory Reid, 53 percent to 42 percent in 2010. Sandoval won a second term earlier this month, capturing more than 70 percent of the vote.

“They are very, very worried about Sandoval,” Nevada political analyst Jon Ralston said of Reid and his advisers. “Everything he does now can be seen through that prism.”

“The last time the President issued a politically motivated executive order to change our immigration laws, he precipitated a crisis at our border, leaving thousands of children at risk and ripping apart the families he claims to want to protect. Granting amnesty does not secure our borders. Sadly, rather than trying to solve our country’s immigration problems, the President’s actions are intended to poison the legislative process at a time when he should be working to bring Americans together.

“If he believed that his actions were urgent and that he had the constitutional authority all along, why did he wait six years into his presidency to act? If he believed he was doing the will of the American people and acting in the best interests of American workers and those waiting in line to become Americans, why did he wait until after this last election?”

There’s another reason that Obama went 50,000 feet rather than 50 feet in his speech. The technical and legal process he is using to issue this executive action isn’t all that popular. An NBC-WSJ poll released Wednesday night showed 48 percent of respondents opposed Obama’s decision to address the immigration issue via executive action while 38 percent supported him doing so. On the other hand, the broader idea of doing something about the millions of people in the country illegally — up to and including offering them some sort of path to citizenship, which Obama is not doing — is far more popular.

Given those political realities, a speech that spends almost no time on how the sausage is made and almost all of the time on the supposed deliciousness of the end product is more likely to be received well.

Obama’s address is the first skirmish in a massive fight coming over his executive action. If the speech is any indication, Obama’s strategy will be to go big, rhetorically speaking, in hopes of avoiding being dragged into the weeds. Easier said than done.