The Department of Homeland Security distanced itself again on Tuesday from a Republican proposal that critics have described as opening the door to civil rights abuses.

DHS Secretary Jeh Johnson told Sen. Ted Cruz (R-Texas) that legislation he drafted, which would strip citizenship from American nationals fighting for US-designated Foreign Terrorist Organizations, was not “the most effective tool” for officials conducting counterterrorism operations.

Johnson made the remarks in testimony before the Senate Judiciary Committee.

Cruz suggested that Secretary of State John Kerry should be lobbying for the bill to pass, despite the fact that he, too, has said that the proposal isn’t necessary.

“There’s existing legislation on the book that provides for other grounds for forfeiting your citizenship,” Cruz told Johnson. “But right now, joining a Foreign Terrorist Organization is not one of those.”

Similar legislation, albeit somewhat narrower in scope, advanced with bipartisan support last Thursday through the House Foreign Affairs Committee.

When asked by The Sentinel for comment on the proposal, a State Department official said after the mark-up that “The Department does not comment on pending legislation.”

During the hearing, only one member, Rep. Alan Grayson (D-Fla.) raised doubts that the bill would pass judicial review.

“The Supreme Court has recognized that there is a Constitutional right to travel. And I think that comes directly from the right of freedom of assembly under the First Amendment,” said Grayson, a lawyer who used to specialize in government contactor law. “Therefore, in my view, and I hope this becomes part of the record on this, I don’t think that you can promptly deny someone a passport or the right to travel without clear and convincing evidence.”

Republicans on the committee, including chair Ed Royce (R-Fla.) and Rep. Ted Poe (R-Texas), the author of the so-called FTO Passport Revocation Act of 2015, argued that the bill was Constitutionally sound. Royce said civil liberties concerns motivated the legislation’s backers “to provide permissive authority to the State Department.”

Grayson responded that the Supreme Court’s current “clear and convincing evidence” justification on the prerequisite for the rescinding of passports “is and should be the standard of proof.”

Secretary of State John Kerry already has the power to deny US citizens of the right to use a valid passport—an authority he famously exercised in the summer of 2013, when he left NSA contractor-turned-whistleblower Edward Snowden stranded at Sheremetyevo Airport in Moscow. The Russian government has since granted him temporary asylum.

The move by Kerry to refuse Snowden his right to travel caused an outcry from some, including the whistleblower himself, about due process violations.

In one high profile incident involving the status of citizenship and counterterrorist operations, former Secretary of State Hillary Clinton revoked the passport of US national Anwar Al-Awlaki six months before he was controversially executed by drone in 2011, after President Obama authorized the strike.

In testimony late last year, Robert Bradtke, a State Department adviser on the conflict on Syria explained to the House Foreign Affairs committee why it hasn’t given the Snowden treatment to any suspected American members of the Islamic State in Iraq and Syria (ISIL).

“This is something we would only do in relatively rare and unique circumstances,” he said. “We would only do it also in consultations with law enforcement authorities, and we have not yet had any requests from law enforcement authorities to cancel passports of [ISIL] or foreign fighters.”

Kerry also told Congress in September that he hadn’t rescinded the right to travel to US passport-holders fighting in Syria because of concerns it could derail criminal investigations.

On Tuesday, Homeland Security Secretary Johnson told Cruz that roughly 180 American citizens have or have attempted to join the conflict in Iraq and Syria, but noted that the actual sum is probably higher by now.

When Sen. Cruz first introduced his legislation—to direct the State Department to consider a US national joining a FTO as having “constructively forfeited his or her American citizenship,” as he told Johnson—it was blasted by critics concerned that it would leave Americans vulnerable to human rights abuses.

“As Law Professor Patrick Wiel points out, while the revocation of the right to travel for security reasons may pass constitutional muster, it is less clear whether the government may deprive an individual of their right to a legal identity as an American citizen,” an American University Law School student-run publication noted in January, shortly after Cruz introduced the Expatriate Terrorists Act for the second time.

David Cole, a Georgetown University law professor and volunteer for the Center for Constitutional Rights, in roundly lambasting Cruz’s proposal last September, described US citizenship as an inalienable right, unassailable by legislation.

“Just as one could not strip an accused criminal of his rights to a jury trial against his will, or strip a member of a church of his religious freedom against his will, so Congress cannot strip citizens of their citizenship against their will,” he argued.

When Cruz first introduced the bill last September, White House Press Secretary Josh Earnest declined to take a position on it. The Administration still has not said whether it would veto the measure or the similar legislation that advanced Thursday through the House Foreign Affairs Committee, in spite of prior criticism expressed by Kerry, Johnson and other administration officials.