Each year, the million or so students applying to college through the Common App are given the option to check a box, disclosing whether they identify as Hispanic, Asian, Black or white, among other choices.

Now, with the U.S. Supreme Court expected to rule soon against race-conscious admissions — and with colleges wanting to follow the law — the Common App has made a pre-emptive move on what is known as the “race box.”

Beginning Aug. 1, colleges will be able to hide the information in those boxes from their own admissions teams, said Jenny Rickard, chief executive of the Common App, in an interview.

The new option will help colleges comply “with whatever legal standard the Supreme Court will set in regards to race in admissions,” Common App said in a statement. A nonprofit, Common App administers a universal application used by more than 1,000 colleges and universities.

The decision, which appears to be aimed at immunizing colleges from litigation, is one of the first concrete examples of how college admissions may be transformed if the Supreme Court bans or restricts race-conscious admissions. The college opt-out could also put more pressure on applicants to signal their racial and ethnic background through other means, primarily in essays or teacher recommendations.

The scope of the court’s decision, expected in late June, is unknown. But the justices showed a keen interest in the use of race boxes during the oral arguments last fall.

Colleges have said they will follow the law, but are wary of future litigation. Groups opposed to affirmative action have said that they may file lawsuits that could test the boundaries of the Supreme Court’s ruling.

The potential case against race boxes is obvious, according to Edward Blum, founder of Students for Fair Admissions, the plaintiffs in the current court cases against Harvard and the University of North Carolina.

“If racial preferences are determined to be illegal, then it must follow that racial classification boxes should not be allowed on college application forms,” he said.

Masking the race boxes on the Common App could give universities a measure of plausible deniability, legal experts said, and perhaps some protection from lawsuits.

Essays are a less likely target for lawsuits. As a practical matter, it would be hard to redact mentions of race from the many thousands of application essays that colleges receive every year, with more than 50,000 applicants at Harvard alone.

But more litigation around the broader issue of diversity, like scholarships for Black students, seems likely. “There is a colossal, well-organized, well-funded attack agenda,” said Art Coleman, managing partner of Education Counsel, a consulting firm working with universities on the Supreme Court cases.

During oral arguments, the Supreme Court justices spent considerable time discussing the race box and the application essay. Some variant of the phrase “checking the box” was used more than 30 times during the five hours of argument before the justices last October.

Patrick Strawbridge, a lawyer for Students for Fair Admissions, sparred with the justices over when it would be appropriate for admissions officers to know the race of an applicant. He suggested that much would depend on the context of the revelation.

“What we object to is a consideration of race and race by itself,” Mr. Strawbridge told the justices.

“Race in a box-checking way, as opposed to race in an experiential statement?” Justice Amy Coney Barrett, one of the conservative majority expected to be sympathetic to the plaintiffs, elaborated.

Mr. Strawbridge said it would be harder to object to a thoughtful essay that invoked the student’s race in the context of a highly personal story.

An essay about overcoming racial discrimination could be permitted, because it “obviously indicates that the applicant has grit, that the applicant has overcome some hardship,” Mr. Strawbridge told the justices. “It tells you something about the character and the experience of the applicant other than their skin color.”

Isiaah Crawford, president of the University of Puget Sound, said he hoped the court would agree with Mr. Strawbridge on that point.

“We certainly do believe that student applicants should have a First Amendment right to be able to speak about their background if they choose to do so,” Dr. Crawford said.

If discussion of a student’s race were fully barred, he said, a white applicant to an Ivy League school might be able to write about being the child of an alumna, while a Black student might not be able to “to talk about his or her background, whose grandparents weren’t let into schools like the Ivy League, and how that has impacted their choices.”

The Common App will continue to collect racial information for its own purposes, like looking at trends in applications among different groups, regardless of how the Supreme Court decides, Ms. Rickard said. Because the nonprofit does not admit students, it is unlikely to be a target of litigation.

Colleges will be able to suppress racial information from both the printable and digital forms of applications. The Common App already allows colleges to hide information about test scores if they do not consider test scores in admissions. Colleges have also been able to hide students’ Social Security numbers, birth dates, gender and criminal history.

Mr. Coleman said he hoped the court’s focus during oral arguments on checking the box meant that it would rule against only the most simplistic and stereotypical use of race in admissions.

Otherwise, he said, trying to hide an applicant’s race could become an exercise in absurdity. For instance, during an applicant’s interview, “Are you supposed to go behind a curtain?”