America’s sometime ritual — looking to the Supreme Court for legal direction on key social issues — was performed multiple times last week as the court handed down landmark decisions that upheld affirmative action in college admissions and struck down sodomy laws.

But Americans often have an inverted sense of what happens on those momentous days when a court opinion is released. We put the justices on high pedestals and imagine their search for “truth” — inviolable legal precedents, sacred talismans to decipher the Constitution.

We think court opinions direct American social behavior.

But they usually just reflect it.

How do these esteemed justices interpret the murky words of the Constitution? “In an important sense,” said Michael Klarman, a constitutional-law expert at the University of Virginia, “they make it up.”

This can offend our sensibilities — and disturb the myths we hold about our most revered government institution.

“There’s incredible reverence for the court,” said Nathaniel Persily, a constitutional law expert at the University of Pennsylvania, “partly because people don’t understand what they do.”

Justices who dissent from majority opinion in these cases may tap into the myth and claim the objective legal high ground, as Justice Antonin Scalia did last week. In his dissent on the sodomy decision, the court, he sputtered, had “taken sides in the culture war.”

But, as Scalia well knows, that has nearly always been how the high court operates. Because the Constitution is so vague, “the justices … have great freedom of interpretation,” said Robert Reinstein, dean of Temple University’s law school.

“Each phrase in the Constitution is like a window,” said Mark Rahdert, another Temple constitutional law expert. “There’s a whole landscape outside, and it’s up to the court to explain what’s out there.”

What’s out there changes as American society changes. How else can one explain that the court found segregation constitutional (1896, Plessy v. Ferguson) and six decades later declared it unconstitutional (1954, Brown v. Board of Education)? The Constitution hadn’t changed in that time — but society had.

And on Thursday, the court found that sodomy laws were unconstitutional — reversing its decision of just 17 years ago.

Consider these examples, which Klarman cites in his book, “From Jim Crow to Civil Rights,” due out this year:

The court did not declare segregation unconstitutional until 1954 — at the cusp of the civil-rights movement.

The court began rendering opinions that recognized rights for the poor in the 1960s, amid the War on Poverty.

The court began declaring laws discriminatory against women during the women’s liberation movement.

The recent majority opinion in Grutter v. Bollinger, upholding affirmative action in college admissions, is no different. Although public opinion seems split on the practice, multiculturalism has become so widespread that the decision doesn’t surprise, Klarman said.

When major corporations, academic institutions and retired generals wrote briefs arguing that affirmative action was essential to the way the nation functions, Justice Sandra Day O’Connor, writing for the majority, took note. The generals argued that affirmative action at their service academies ensured a qualified diverse military leadership, essential to national security.

Again, society’s needs and behavior guided the court. National security proves a compelling argument.

Even the court’s very power to declare laws unconstitutional — nowhere explicitly stated in the Constitution — evolved. There was much dispute over the issue at the Constitutional Convention. But over several decades, it became more accepted. And by the time Justice John Marshall declared, in the 1803 case Marbury v. Madison, that the court indeed had the right of judicial review, it was not controversial.

There have long been two strains of thinking about how to interpret the Constitution, which mirror the age-old debate about how to interpret the Bible — literally or figuratively. One strain holds that the court must discern the original intent of the Constitution’s authors and adhere strictly to their thinking. Such adherents include Scalia and Justice Clarence Thomas.

The other strain holds that the Constitution is a living document whose interpretation can change to reflect changing society. In the decision striking down sodomy laws, Justice Anthony M. Kennedy noted that the authors of the 14th Amendment “knew times can blind us to certain truths, and later generations can see that laws once thought necessary and proper, in fact, serve only to oppress. As the Constitution endures, persons in every generation can invoke its principals in their own search for greater freedom.”

Even if everyone agreed on seeking only the original intent of the Constitution’s authors, there is rare consensus on what they did mean.

For instance, central to the affirmative-action case was the first clause of the Constitution’s 14th Amendment, which ends like this: ” … nor shall any state … deny to any person within its jurisdiction the equal protection of the laws.”

Vague? You bet. Some justices over the years, including Scalia and Thomas in dissents on affirmative action, argued that the amendment was intended to ensure color-blind behavior by the government. But some legal experts say it is hard to justify that position, based on the Congress that passed the amendment.

“There are almost as many views on what the amendment means as there were senators and representatives who commented from the floor,” Rahdert said.

Can one really assume the original architects meant complete color-blindness? The same Congress that approved the equal-protection amendment also established freedmen’s bureaus, to give specific aid to former slaves.

Klarman, in his book, puts it this way: “Constitutional law generally has sufficient flexibility to accommodate dominant public opinion, which the justices have little inclination, and limited power, to resist.”