By Joan Biskupic, CNN legal analyst & Supreme Court biographer

(CNN) — Supreme Court officials are escalating their search for the source of the leaked draft opinion that would overturn Roe v. Wade, taking steps to require law clerks to provide cell phone records and sign affidavits, three sources with knowledge of the efforts have told CNN.

Some clerks are apparently so alarmed over the moves, particularly the sudden requests for private cell data, that they have begun exploring whether to hire outside counsel.

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The court’s moves are unprecedented and the most striking development to date in the investigation into who might have provided Politico with the draft opinion it published on May 2. The probe has intensified the already high tensions at the Supreme Court, where the conservative majority is poised to roll back a half-century of abortion rights and privacy protections.

Chief Justice John Roberts met with law clerks as a group after the breach, CNN has learned, but it is not known whether any systematic individual interviews have occurred.

Lawyers outside the court who have become aware of the new inquiries related to cell phone details warn of potential intrusiveness on clerks’ personal activities, irrespective of any disclosure to the news media, and say they may feel the need to obtain independent counsel.

“That’s what similarly situated individuals would do in virtually any other government investigation,” said one appellate lawyer with experience in investigations and knowledge of the new demands on law clerks. “It would be hypocritical for the Supreme Court to prevent its own employees from taking advantage of that fundamental legal protection.”

Sources familiar with efforts underway say the exact language of the affidavits or the intended scope of that cell phone search — content or time period covered — is not yet clear.

The Supreme Court did not respond to a CNN request on Monday for comment related to the phone searches and affidavits.

The young lawyers selected to be law clerks each year are regarded as the elite of the elite. (Each justice typically hires four.) They are overwhelmingly graduates of Ivy League law schools and have had prior clerkships with prominent US appellate court judges.

Their one-year service becomes a golden ticket to prestigious law firms, top government jobs or professorships. Six of the current nine Supreme Court justices are former clerks.

The escalating scrutiny of law clerks reflects Roberts’ concerns about the breach in confidentiality and possibly further leaks. It also suggests the court has been so far unsuccessful in determining Politico’s source.

Roberts ordered the investigation on May 3, designating the court’s marshal, Gail Curley, to lead the probe.

Curley, a lawyer and former Army colonel, oversees the police officers at the building. She is best known to the public as the person who chants, “Oyez! Oyez! Oyez!” at the beginning of the justices’ oral argument sessions. The marshal’s office would not normally examine the details of cell phone data or engage in a broad-scale investigation of personnel.

The investigation comes at the busiest time in the court’s annual term, when relations among the justices are already taut. Assisted by their law clerks, the justices are pressing toward late June deadlines, trying to resolve differences in the toughest cases, all with new pressures and public scrutiny.

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Because of protests and security concerns related to the Mississippi abortion case, the court building is surrounded by an 8-foot non-scalable fence and concrete barriers.

The justices are also resolving a New York dispute that could, based on their remarks during oral arguments in November, expand Second Amendment protection for gun owners. Additionally, the court could further lower the wall of separation between church and state by permitting certain prayer at public schools and requiring public vouchers for religious institutions.

The draft opinion in the case of Dobbs v. Jackson Women’s Health Organization was written by Justice Samuel Alito and appeared to have a five-justice majority to completely reverse the 1973 Roe v. Wade decision. That landmark ruling made abortion legal nationwide and buttressed other privacy interests not expressly stated in the Constitution. Some law professors have warned that if Roe is reversed, the Supreme Court’s 2015 decision declaring a constitutional right to same-sex marriage could be in jeopardy.

Publication of the Alito draft opinion has already prompted national protests and dueling state legislative efforts — to further eliminate all options for a woman seeking to terminate a pregnancy or, alternatively, to try to safeguard women’s access to abortion where possible.

But it is difficult for anyone outside the building to know whether the Alito draft still commands a majority on a court tightly divided on abortion rights and split over how quickly to reverse precedent.

Scrutiny of a secretive group

As the justices continue their secret negotiations, the scrutiny of the law clerks is heating up.

The clerks have been the subject of much of the outside speculation over who might have disclosed the draft, but they are not the only insiders who had access. Alito’s opinion, labeled a first draft and dated February 10, would have been circulated to the nine justices, their clerks, and key staffers within each justice’s chambers and select administrative offices.

If tradition was followed, copies were sent electronically and, separately, printed out and hand-delivered to chambers by aides to the marshal.

Other employees connected to the nine chambers would have had some access to the opinion. CNN could not verify that number, but former law clerks say the document could have been sent through regular channels to nearly 75 people. It is not known if court officials are asking employees who are part of the permanent staff, beyond the one-year law clerks, for their phone records.

Cell phones, of course, hold an enormous amount of information, related to personal interactions, involving all manner of content, texts and images, as well as apps used. It is uncertain whether details linked only to calls would be sought or whether a broader retrieval would occur.

There are protocols for handling drafts of court opinions, which circulate electronically on a closed system, separate from the computer system the justices and court employees use to communicate with people outside the court. Yet it is possible for printed copies to leave the building under even innocent circumstances, as work is taken home.

Court officials are secretive even in normal times. No progress reports related to the leak investigation have been made public, and it is not clear whether any report from the probe will ever be released.

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