With voters now ranking terrorism as the top problem facing the U.S. for the first time in a decade, and Cruz is currently projected to win the Iowa caucus next week, the Expatriate Terrorist Act is one of Cruz’s most frequently-promoted policy proposals to deal with the issue. The Senate Judiciary Committee will consider the bill this Thursday.

What the bill would do

“I think what we need is a commander in chief who is focused like a laser on keeping this country safe and on defeating radical Islamic terrorism. What should we do?” asked Sen. Ted Cruz (R-TX) during the most recent Republican presidential debate. “First, we should pass the Expatriate Terrorist Act, legislation I’ve introduced that says if an American goes and joins ISIS and wages jihad against America, that you forfeit your citizenship and you can not come in on a passport.”

Cruz introduced the bill, S. 247, in conjunction with the House companion bill H.R. 503 by Rep. Steve King (R-IA4). The legislation would amend the Immigration and Nationality Act (INA) to include serving in or aiding a terrorist organization as grounds for loss of U.S. citizenship. While the INA currently includes “terrorism-related activity” as grounds to exclude people from gaining U.S. citizenship, with provisions added several times to broaden the scope of those excluded, most notably after 9/11, it doesn’t automatically strip U.S. citizenship from citizens who engage in “terrorism-related activity.” Cruz’s bill, if passed, would do just that.

Cruz has said, “As long as our border isn’t secure, we’re making it far too easy for terrorists to follow through on promises [to attack the United States]… ISIS is a study in oppression and brutality. We should take common-sense steps to make fighting for ISIS a formal renunciation of U.S. citizenship.”

What opponents say

Cruz introduced the same bill last session, in September 2014, but it never received a vote because Sen. Mazie Hirono (D-HI) objected. Hirono said the bill would impact “fundamental constitutional rights, which should be given the full deliberation of the Senate … Legislation that grants the government the ability to strip citizenship from Americans is a serious matter, raising significant constitutional issues.”

Hirono may have been referring to the 1967 Supreme Court decision Afroyim v. Rusk, which found by a 5–4 majority that “Congress has no power under the Constitution to divest a person of his United States citizenship absent his voluntary renunciation.” However, the 2003 case Breyer v. Ashcroft from the Third Circuit Court of Appeals (one level below the Supreme Court in the judicial system) suggested it might be possible to voluntarily renounce one’s citizenship if a person’s actions “constitute a voluntary and unequivocal renunciation of any possible allegiance to the United States of America.”

Davie Bier of the libertarian-leaning Niskanen Center disagrees, writing, “We should not give more power to bureaucrats to take away all of the rights of Americans with a stroke of the pen. Such a process does not accord with American traditions or basic human rights. Congress should reform the expatriation statutes to require a trial prior to loss of citizenship.”

A changing context

The bill may likely move further along in the process this year, though. ISIS, which was a relatively new threat in fall 2014 when Cruz last introduced the bill, is now front and center among America’s most prominent security threats, particularly after November’s Paris attacks. A Justice Department official estimates 250 U.S. citizens have joined or have attempted to join ISIS — a number that may be growing. Additionally, Republicans now hold majority control of the Senate. Both the Senate and House versions of the bill have only attracted Republican co-sponsors so far.