The scene was a festive holiday-season dinner with guests from both Northern and Southern California. The discussion grew serious as the question arose of whether President-elect Trump would really try to set up a national registry of citizen and resident Muslims in America as an anti-terror tactic – which he advocated while running for office – with no one knowing what might come next.

“If that happens, I would immediately go and register as one,” declared one youthful woman, a non-Islamic mother of two small children.

Days later, 600 computer engineers and programmers for California-based high-tech giants like Google and Twitter said they would refuse to take part in setting up or operating such a database, even if it cost them their high-paying jobs. This defiant list has now surpassed 2,000.

Mr. Trump’s staff, however, says he never advocated a registry based on religion, but when asked about it in an NBC-TV interview in November 2015, he said “Oh I would certainly implement that. Absolutely.”

All this evoked the actions of Danish citizens when German leader Adolf Hitler ordered a roundup of occupied Denmark’s 7,800 Jews on Oct. 1, 1943, in the midst of his World War II campaign to exterminate Europe’s 6 million Jews.

Christian Danes first alerted all Danish Jews to hide, then staged a two-night boatlift taking more than 7,200 Jews across a narrow strait from Helsingor (Shakespeare’s Elsinore), north of Copenhagen, to neutral Sweden.

The Danes’ King Christian X became a historic hero by actively encouraging this.

It is uncertain that Mr. Trump will order a Muslim registry, although his transition team’s chief advisor on immigration, Kansas Secretary of State Kris Kobach, has said he advised Mr. Trump to establish a list of immigrants and visitors from countries where terrorist organizations are active. Read: refugees and others from predominantly Islamic places like Syria, Iran, Iraq, Egypt, Pakistan, Afghanistan, Libya, Morocco, Tunisia, Sudan, Somalia and Algeria.

What About Japanese?

Some Trump allies cited as a legal precedent for such a registry the roundup and internment of Japanese-American Nisei in remote, primitive camps just after the Pearl Harbor attack that brought America into World War II. Never mind that the U.S. government under President Reagan long ago apologized and paid reparations for those actions.

Mr. Kobach, a longtime anti-illegal immigrant activist, wrote Arizona’s 2010 SB 1070, which required police to stop anyone who looked like an immigrant (read: Latino) and demand documents showing they were authorized to be in this country. Courts later declared the law unconstitutionally discriminatory.

Any registry or database of the type Mr. Trump proposed during his campaign would probably need cooperation from America’s large high-tech companies, most headquartered in this state, just as President George W. Bush’s post-9/11 effort to track phone traffic by potential terrorists needed cooperation by the likes of AT&T and Verizon. But the subject did not arise when more than a dozen mostly-Californian high-tech moguls met with Mr. Trump in mid-December.

At first, only California-based Twitter and Facebook took refusal stances on any such Muslim registry. Later, Apple, Google, IBM, Uber and Microsoft jointed them, possibly prodded by the stances of thousands of their employees.

When TheIntercept.com, a self-described “adversarial journalism” website, asked major tech firms what they would do about a registry,

Microsoft initially said “We’re not going to talk about hypotheticals at this point,” and provided a link to a company blog advocating “not just diversity among all the men and women who work here, but inclusive culture.”

What several companies at first did not see, but Twitter and Facebook apparently understood right away, was that if they said nothing they would be tacitly approving the idea of a religion-based list.

The moral question here is similar to what confronted Danes in 1943, even if the potential consequences for people resisting a Muslim list or database are far less threatening than the shoot-on-sight tactics carried out by Nazi SS troopers when they encountered or caught someone defying an occupation regime order.

The bottom line: Tarring all Muslims as potential terrorists would be a form of discrimination somewhat comparable to rounding up America’s Nisei, especially since the vast majority of Islamic-Americans have absolutely no interest in or record of promoting anything anti-American.

Mr. Elias may be contacted at www.tdelias@aol.com

His book, “The Burzynski Breakthrough: The Most Promising Cancer Treatment and the Government’s Campaign to Squelch It,” is now available in a soft cover fourth edition. For more Elias columns, go to www.californiafocus.net