WASHINGTON — Not so long ago, conservatives found it maddening when U.S. judges cited foreign law in their decisions interpreting the Constitution.

When the Supreme Court took account of international trends in a 2005 decision eliminating the juvenile death penalty, for instance, Justice Antonin Scalia wrote a furious dissent. “The basic premise of the court’s argument — that American law should conform to the laws of the rest of the world — ought to be rejected out of hand,” he wrote.

The justice also accused his colleagues of opportunism and hypocrisy. In other areas of the law, he wrote, the court had ignored conservative foreign decisions on criminal procedure, religion and, notably, abortion. “To invoke alien law when it agrees with one’s own thinking, and ignore it otherwise, is not reasoned decision-making, but sophistry,” Justice Scalia wrote.

Lawmakers in Mississippi appeared to take a different view in 2018, when they enacted a law banning most abortions after 15 weeks.

In the first legislative finding justifying the law, its drafters looked abroad for support. “The United States is one of only seven nations in the world that permits nontherapeutic or elective abortion-on-demand after the 20th week of gestation,” the finding said. “In fact, fully 75 percent of all nations do not permit abortion after 12 weeks’ gestation, except (in most instances) to save the life and to preserve the physical health of the mother.”

The law was a calculated challenge to Roe v. Wade, the 1973 decision that established a constitutional right to abortion and prohibited states from banning the procedure before fetal viability, or around 23 or 24 weeks. The Supreme Court will hear arguments in December in a challenge to the law.

The lawmakers’ statements about foreign practices appear to be generally correct. A fact-checking column in The Washington Post in 2017 largely confirmed the first one: “This statistic seemed dubious at first, because it seemed extreme for just seven countries out of 198 to allow elective abortions after 20 weeks of pregnancy,” it said. “But upon further digging, the data back up the claim.”

And 12 weeks is a common nominal limit, said Mary Ziegler, a law professor at Florida State University, though the social context is usually quite different.

“Most places in the world have something like 12 weeks, but with public health insurance,” she said. “They pay for it. If you want to have an abortion in the first 12 weeks, there’s no real reason that you can’t.”

Martha F. Davis, a law professor at Northeastern University, added that the limits were usually subject to significant exceptions for patients who needed later abortions.

“Many nations, but not all, and not our closest peers, have cutoffs that on paper are pre-viability,” she said. “But they make very many exceptions that allow abortion much more liberally.”

At his confirmation hearings in 2005, Chief Justice John G. Roberts Jr. questioned the use of foreign law in U.S. constitutional cases, saying it was bound to be selective.

“In foreign law, you can find anything you want,” he said. “Looking at foreign law for support is like looking out over a crowd and picking out your friends.”

In a Supreme Court brief, officials in Mississippi focused on the nation’s adversaries. “The United States finds itself in the company of China and North Korea as some of the only countries that permit elective abortions after 20 weeks’ gestation,” the brief said.

Lawyers for the abortion providers challenging the Mississippi law asked the court to consider other nations.

“In countries with legal traditions and democratic values most comparable to the United States, such as Great Britain and Canada, abortion is legal until at least viability,” they wrote. “And many countries that have limits earlier in pregnancy continue to permit abortion for broad social and health reasons after that point, functionally allowing abortion later in pregnancy.”

Dueling friend-of-the-court briefs in the Mississippi case also supported Chief Justice Roberts’s observation about selectivity.

In one brief, international law professors supporting the Mississippi law said that “France, Italy, Germany, Spain, Norway and Switzerland have a gestational limit of 14 weeks or earlier for abortion on demand, allowing later exceptions only on restricted medical grounds.” The brief cited data gathered by the Center for Reproductive Rights.

On the other side, a brief from another set of international and comparative law scholars supporting the abortion providers in Mississippi focused on the countries that it said had similar legal traditions to the United States, notably Canada, New Zealand and Britain, which “permit abortion up to or around viability.”

“Beyond their broadly permissive laws,” the brief said, “these countries also support abortion rights and reproductive decision-making through universal health care, access to abortion services and access to contraception.”

The brief added that recent international trends had been toward easier access to abortion, with more than 50 countries liberalizing their laws in the past 25 years. By contrast, the brief said, overruling Roe “would put the United States in the company of countries like Poland and Nicaragua as one of only a few countries moving towards greater restrictions on legal access to abortion in the past 20 years.”

Professor Ziegler said there was something artificial about the recent conservative attentiveness to foreign nations with roughly 12-week limits.

“People who are anti-abortion are disingenuous about this, because they’re not proposing 12 weeks,” she said. “They’re proposing six weeks, or they’re proposing fertilization.”