When Donald Trump became president, he swore an oath to uphold the Constitution and enforce federal laws "faithfully." James Madison, who was the scrivener at the Constitutional Convention, insisted on using the word "faithfully" in the presidential oath and including the oath in the body of the Constitution because he knew that presidents would face the temptation to disregard laws they dislike.

The employment of the word "faithfully" in the presidential oath is an unambiguous reminder to presidents that they must enforce federal laws as they are written, not as presidents may wish them to be. Earlier this month, Trump succumbed to Madison's feared temptation, and last week, a federal judge corrected him. Then an uproar ensued.

Here is the back story.

Federal immigration laws, as well as treaties to which the United States is a party, require that foreigners who are seeking asylum here may enter the United States across any border they can reach, whether at a designated portal or not. If they have not entered through a designated portal, they can be brought, without a warrant, to a portal for processing.

The feds must process all asylum applications from migrants who make prima-facie cases for asylum. Once an application has been made, the feds may release the migrant (as President Barack Obama did) into the general population, or they may detain the migrant (as President Trump has done), pending a trial before a federal immigration judge.

At the trial, the migrant has the burden of proving worthiness for asylum. That worthiness can be based only on government animosity toward the migrant or government failure to protect human rights and enforce property rights in the home country. If the migrant prevails at trial, asylum is granted, and a green card is issued. If not, deportation follows.

On Nov. 9, President Trump issued a proclamation directing the Border Patrol to deny entry to all migrants, including those with legitimate asylum claims, unless they come through government portals where Border Patrol personnel are present to address their applications. Though this sounds reasonable, it directly contradicts federal law, which expressly permits migrants to enter the U.S. anywhere.

When groups of migrants challenged Trump's order in federal court in San Francisco, Judge Jon Tigar prevented the government from complying with the president's proclamation. The judge did not make any value judgments, nor was he critical of the president's motivation. Rather, he ruled that the law is clear: Immigrants seeking asylum may enter anywhere, and the president cannot change federal law; only Congress can.

Trump dismissed Judge Tigar's ruling as meritless because the judge was appointed to the bench by former President Obama. The implication in Trump's words was that Judge Tigar ruled against him for political reasons. In reality, Judge Tigar did what any judge would do; he prevented the president from changing federal law and required him to enforce the immigration laws as Congress has written them — and to do so faithfully.