David B. Rivkin Jr. practices appellate and constitutional law in the District and served in the Justice Department under Presidents Ronald Reagan and George H.W. Bush. Karen Tumlin is legal director for the National Immigration Law Center and the NILC Immigrant Justice Fund.

Editor’s note: On Friday, U.S. District Judge James L. Robart issued a ruling temporarily halting enforcement of President Trump’s executive order barring entry to the U.S. for citizens of seven majority-Muslim countries. On Monday evening, David Rivkin and Karen Tumlin exchanged views and predictions about the legal fight over the executive order. The email discussion was moderated by Post Opinions digital editor James Downie and has been edited for style and clarity.

Karen Tumlin: Hi, James and David, looking forward to having this discussion with you both on this important topic.

The executive order has several legal problems. I would highlight two of the most serious. First, ours is a nation that was founded on the premise that individuals should be free from religious discrimination by the government. That principle is enshrined in our Constitution and prohibits the federal government from discriminating against or favoring any religious group. This executive order does both. By banning the entry of individuals with valid visas from seven majority-Muslim countries, there is no question that the executive order singles out Muslims for disfavored treatment. Equally questionable is the preference given to minority religions under the executive order for refugees. Practically, this favors the admission of Christians.

Second, the executive order also violates the bedrock legal principle of equal protection under our laws. That constitutional guarantee means that the federal government cannot discriminate against individuals based on what they believe (their religion) or where they were born, without adequate rationale.

David B. Rivkin Jr.: Karen is jousting at a straw man. This executive order, by its very terms, does no more than suspend for 90 days entry for individuals from seven countries that have been identified as posing a heightened risk of terrorism and where the conditions on the ground do not allow for high-quality vetting. The language of the executive order aside, there are more than 50 Muslim-majority countries in the world, and the vast majority of them are not affected by this order.

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In addition to the rewriting of the order, Karen ignores the fact that the statutory and constitutional authorities overwhelmingly support the president’s ability to issue such an executive order. First, Congress expressly granted the president broad discretionary and non-reviewable authority to “suspend the entry of all aliens or any class of aliens . . . or impose on the entry of aliens any restrictions he may deem to be appropriate” if he finds that such an entry “would be detrimental to the interests of the United States.” This authority, by the way, has been utilized by numerous past presidents, including both Presidents Bush, President Bill Clinton and President Barack Obama.

Second, in addition to this broad delegation of authority from Congress, the president has inherent, formidable constitutional authority of his own over foreign affairs and national security, with the power to control immigration being an integral part of those authorities. So, here we have two political branches that have spoken in unison on this issue, placing the president in the strongest possible legal position. Last but not least, well-established Supreme Court precedents indicate that states — like the states of Washington and Minnesota — have no equal-protection rights of their own, nor can they vindicate equal-protection rights of their citizens. The same is true about being able to challenge alleged religious discrimination. This limitation on the states’ authority to champion such claims is fundamental to our separation-of-powers architecture.

Tumlin: When looking at the legality of this executive order, we have to look back to the very clear, discriminatory intentions for the order that were laid down repeatedly on the campaign trail by then-candidate Trump to create a ban on the entry of Muslims to the United States. The text of the executive order serves to implement that shameful campaign promise, as do statements by the president and the drafters of the order since its signing. Our Constitution does not stand for this kind of governmental discrimination.

You don’t have to discriminate against every Muslim in the world to run afoul of our Constitution’s protections and human decency.

The executive order doesn’t make us safer as a country, it puts us more at risk. But don’t just take my word for it. Have a look at the declaration submitted Monday at the U.S. Court of Appeals for the 9th Circuit by a host of national security ex-officials from both sides of the aisle noting that in their “professional opinion, this Order cannot be justified on national security or foreign policy grounds.”

Rivkin: I disagree. There are a few instances that arise in the unique context of domestic equal-protection challenges to governmental actions that are facially neutral but produce substantial discriminatory impacts on groups of people, based on such suspect classifications as race, nationality, ethnic origin, etc. This doctrine has never been used in foreign affairs, both because of the tremendous judicial deference owed in this area to the two political branches and because discerning the intentions of the president is particularly difficult in the national security area, given the inherent lack of judicial competence in foreign affairs and lack of access to classified information.

And, as a practical matter, under your logic, courts would rule differently on the constitutionality of exactly the same executive orders, suspending entry of certain types of aliens — with Obama’s order delaying the entrance of refugees from Iraq and President Ronald Reagan’s suspending the entrance of certain Cuban nationals — depending on how they felt about the subjective intentions of a given president. This cannot possibly be true.

And, to reiterate, as far as the judgments regarding whether or not this order makes us safer, such judgments are uniquely unsuited for judicial discernment and the judiciary is barred from engaging on them on the basis of the Supreme Court’s case law, known as the political question doctrine. The fact that some former national security officials challenge the policy wisdom of the order, while other national security officials — most notably those of this administration — support it, merely demonstrates that these are policy disputes that the judiciary is both ill-equipped and constitutionally barred from arbitrating.

James Downie: Karen, how would you respond to the argument that the president has the authority to enact this order?

Tumlin: The president is not king. He, too, must abide by our Constitution as well as the immigration laws duly written and passed by Congress. What the president has done here is attempt to hastily legislate by executive fiat. The result has been confusion among federal officials unsure of how to interpret or implement this presidential dictate and very real human suffering. And let’s be clear, this executive order does not only target non-U.S. citizens living abroad. It has profound consequences on U.S. citizens who can’t bring their parents in to witness the birth of a child, or on businesses that can’t send their most talented U.S.-based executives abroad for important meetings. And the order has left others in limbo overseas who may have taken a trip abroad to, for example, visit an ill relative, and unless the Washington state decision stands will not be able to return to their families and jobs in the United States because their validly issued visa vanished overnight.

Downie: David, can you expand on the argument that it’s not discriminatory against Muslims? Ilya Somin elsewhere on The Post’s site writes, “The unconstitutional motive behind Trump’s order can’t be sidestepped by pointing out that it blocks some non-Muslim refugees too. Poll taxes and literacy tests excluded a good many poor whites from the franchise, but were still clearly aimed at blacks.” What are your thoughts on that?

Rivkin: My argument is focused on the fact that a relatively small percentage of the world’s Muslim countries are impacted by this order. Stated differently, this executive order is a singularly ineffective — in legal parlance, it would be called under-inclusive — form of a Muslim ban. Accordingly, it is not a Muslim ban at all, but a suspension of entrants from seven countries with conditions on the ground that both promote terrorism and make effective vetting impossible. By contrast, poll taxes were very effective in excluding blacks, as well as impacting many poor whites; in legal parlance, they were overly inclusive but nevertheless served their intended discriminatory purpose. This is fundamentally not the case here.

Tumlin: I would humbly submit that a more relevant lens to look at this question is in terms of recent Muslim migration to the United States. For example, 82 percent of all Muslim refugees who entered the United States in fiscal years 2014 through 2016 hailed from the seven countries. The executive order may not use the words “Muslims keep out,” but it certainly would serve to achieve that goal if allowed to stand.

Downie: In closing, how do you expect the 9th Circuit to decide on Robart’s ruling?

Rivkin: I believe that the 9th Circuit will not let Robart’s decision stand. I say this fully appreciating the fact that the 9th Circuit is the most idiosyncratic in the country and the one most often overruled by the Supreme Court. However, given the fact that the case brought by the states is so deeply flawed — they fail both standing-wise and merits-wise — I believe that the 9th Circuit will do the right thing and will rule in a matter of days. I would also expect that, because the plaintiffs in this case lack standing, the 9th Circuit would not only overturn Robart’s temporary restraining order but would dismiss the entire case without ever reaching the merits. If I am wrong and the 9th Circuit fails to do this, I have every confidence that this would be the result reached by the Supreme Court, when it became seized of that case.

Tumlin: I respectfully disagree with David on this always risky judicial crystal ball-gazing. In the 10 days since the executive order was signed, we have seen people take to the streets all across this country to protest it, lawyers like me have taken to the courts to challenge its illegality, and a diverse and stunning cross-section of Americans from every walk of life have questioned its wisdom. All because this executive order stands in sharp contrast with our legal and moral principles as a nation. I have every confidence that the 9th Circuit will let this temporary block on this harmful executive order stand.

It is also worth mentioning that a real question exists as to the propriety of the 9th Circuit weighing in on the district court’s order at all at this time. Generally, temporary restraining orders are not appealable immediately to the higher courts.

Rivkin: In our constitutional system, the extent of political controversies, including the protests, surrounding a given issue is utterly unrelated to the analysis of legality and should have no effect on any court. And whether or not this order is inconsistent with our moral and legal traditions is a classical hortatory declaration, suitable for political debates, and is not a viable legal argument.