Judge Brett Kavanaugh, a finalist to be President Trump’s next Supreme Court nominee, is drawing criticism for his interpretation of the Fourth Amendment, with a prominent Republican calling his views on government call-record collection “troubling.”

Kavanaugh, a judge on the U.S. Court of Appeals for the D.C. Circuit, offered an expansive legal justification for the National Security Agency’s discontinued call record dragnet in a little-noticed November 2015 concurrence.

Privacy activists say Kavanaugh's two-page opinion is remarkable both for its legal analysis and the fact he didn’t need to write it.

[Related: Trump narrows field of possible Supreme Court nominees to three]

If Trump nominates Kavanaugh on Monday, he will do so less than a week after taking a very different approach to government surveillance, calling the NSA’s recent purge of call records “a disgrace,” tweeting about claims of accidental over-collection: “Privacy violations? They blame technical irregularities.”

The once-secret call record program defended by Kavanaugh was exposed by former NSA contractor Edward Snowden in 2013 and was sharply curtailed by Congress in June 2015 amid privacy concerns and questions about whether it ever helped foil a U.S. terror plot.

Kavanaugh’s concurrence sided with colleagues refusing to hear a case against the program, which ingested and stored for five years domestic phone call metadata for potential later use in intelligence investigations.

Kavanaugh wrote that the collection of these records did not constitute a “search” under the Fourth Amendment, citing the third-party doctrine established by the Supreme Court's 1979 decision in Smith v. Maryland — a common perspective among judges.

But he added that even if it was a “search” under the Fourth Amendment, the government was allowed to take the records because it had a “special need” in preventing terrorism, overriding the privacy interests of people whose records were taken without a warrant.

Among the advocates uneasy with his reasoning is Ken Cuccinelli, president of the Senate Conservatives Fund, a group that backs conservative Republican Senate candidates.

“I believe Judge Kavanaugh is an excellent judge, though certainly not a perfect one,” Cuccinelli told the Washington Examiner. "His Fourth Amendment perspective is troubling."

Cuccinelli, a former Virginia attorney general, had represented Kentucky Sen. Rand Paul in a lawsuit challenging the constitutionality of the call-record program. Paul’s case was hitched to conservative legal activist Larry Klayman’s lawsuit in the same circuit. Klayman’s case was the one denied by Kavanaugh.

“As someone who sued the NSA over their metadata gathering as a violation of the Fourth Amendment, he and I disagree on that point, and I think a lot of liberty-minded folks are going to have that as a major concern,” Cuccinelli added.

The concern likely would be bipartisan, although with the Senate so closely divided, the defection of even one Republican senator could threaten the nomination. A spokesman for Paul did not respond to a request for comment.

Others outside of GOP politics are also expressing concern.

George Washington University law professor Jonathan Turley said that Kavanaugh’s concurrence “reflects a sweeping view of national security as an exception to core protections.”

“The concurrence is particularly notable because it is largely dicta,” Turley went on. "Kavanaugh went out of his way to position himself at the outer limits of executive power.

“Notably, it runs against the type of protective approach of recent cases like Carpenter,” he added, referring to a Supreme Court ruling from last month requiring a warrant for authorities to collect cellphone location data.

Jameel Jaffer, executive director of the Knight First Amendment Institute at Columbia University, previously represented the American Civil Liberties Union in a lawsuit against the call record collection and said it would be incongruous for Trump to express concern about surveillance practices, then nominate a forceful backer of the discontinued historical dragnet.

“I don’t want to take a position on the viability or merit of any particular possible nominee, but I think it would be odd and incoherent for a president who has expressed so much concern about the abuse of surveillance power to nominate a judge who went out of his way to declare that he was untroubled by the NSA’s dragnet collection of hundreds of millions of Americans' call records,” Jaffer said.

Attorney Miguel Estrada, a Kavanaugh supporter nominated unsuccessfully for a federal judgeship in 2001, defended the opinion, arguing the "special need" analysis seems to be fall in line with court precedent.

"Judge Kavanaugh was merely pointing out — quite correctly — that the collection of telephone numbers that one dials is not considered a search under the Supreme Court’s decision’s in Smith v. Maryland, and that even if it were, the Supreme Court has also developed a 'special needs' doctrine under the Fourth Amendment that would seemingly apply here," Estrada said.

"If this exemplifies 'deference,' it is deference to the Supreme Court, whose decisions are binding on lower court judges, not deference to the executive branch," Estrada continued. "I note that even after the Supreme Court’s very recent decision in Carpenter, Smith v. Maryland continues to be good law. The Supreme Court was urged to overrule it but did not do so."

Orin Kerr, a Fourth Amendment scholar at George Washington University, said that the brevity of Kavanaugh’s concurrence makes it difficult to thoroughly analyze his viewpoints, but that “Kavanaugh's view was more national-security oriented than privacy oriented, certainly.”

Kerr said that Kavanaugh’s determination that a “search” did not occur was consistent with Supreme Court precedent — “although at least in academic circles that view was controversial” — but that more finely parsing Kavanaugh’s “special need” rationale is difficult because “that would require knowing when a ‘search’ occurred, which was difficult to assess.”

Kavanaugh was nominated to the D.C. Circuit by President George W. Bush and reportedly is a favorite of White House counsel Don McGahn. Other reported finalists include Judge Amy Barrett of the 7th Circuit and Judge Raymond Kethledge of the 6th Circuit. Kethledge’s name emerged as a front-runner more recently.

Also on Trump’s larger list of 25 possible picks is Sen. Mike Lee of Utah, who argued forcefully against the NSA call record program, and who sponsored successful USA Freedom Act legislation in 2015 to end the dragnet.

Lee was one of seven candidates interviewed by Trump for the Supreme Court nomination, but is no longer being mentioned among the finalists in news reports.

In a Thursday statement, Lee was endorsed by Paul and former Sen. Jim DeMint, R-S.C. He had previously been endorsed in an op-ed by Sen. Ted Cruz of Texas. Although he is a conservative favorite, 36 of 49 Senate Democratic caucus members have co-sponsored legislation he authored, including bills to reform criminal sentencing and enhance privacy.

Lee made a political ad touting his opposition to the call record program, and said in a 2015 interview, “The federal government has no business tracking your calling data.”