The effort is being led by California Rep. Zoe Lofgren in the House and Delaware Sen. Chris Coons in the Senate, according to details shared first with CNN. The brief was expected to be filed on Thursday.
In the House, the effort already has more than 65 signatures, including leaders like House Minority Leader Nancy Pelosi, Congressional Hispanic Caucus Chairwoman Michelle Lujan Grisham and Democratic Caucus Chairman Joe Crowley, as well as the top Democrats on the House Judiciary and House Homeland Security committees. The group hopes to have more signatures by the time they file the briefing.
In the Senate, the effort has a dozen signers, including most Democratic members of the Judiciary Committee and its top Democrat, Sen. Dianne Feinstein, and No. 2 Senate Democrat Dick Durbin.
The group is filing an amicus curiae -- or a friend of the court brief -- in the New York case Darweesh v. Trump. The case was brought by two Iraqis, Hameed Khalid Darweesh and Haider Sameer Abdulkhaleq Alshawi, who were granted visas to the US after supporting the US military in Iraq.
When the ban went into effect, Darweesh and Alshawi were detained at John F. Kennedy International Airport, prompting a lawsuit to be filed on their behalf by the American Civil Liberties Union, Yale Law School Clinic, the International Refugee Assistance Project and the National Immigration Law Center. They were eventually allowed to enter the US but their case challenging the constitutionality of the executive order continues. The New York attorney general has intervened to join the case, and supportive amici briefs include major US universities and the Anti-Defamation League.
Issued January 27, Trump's executive order bars citizens of Iraq, Syria, Iran, Libya, Somalia, Sudan and Yemen from entering the US for 90 days, all refugees for 120 days and indefinitely halts refugees from Syria.
The case is similar to but unrelated to the lawsuit in the 9th Circuit, which resulted in a nationwide halt of enforcing the order. Appellate judges refused the Trump administration's request to reinstate the travel ban, but no judges have yet ruled on the constitutional challenges to the order itself. Several lawsuits have been filed nationwide and are working their way through the judicial system.
The Democrats' filing identifies its lawmakers as "committed to ensuring that our immigration laws and policies both help protect the nation from foreign and domestic attacks and comport with fundamental constitutional principles, such as religious freedom and equal protection under the law."
The filing argues that the executive order violates the First Amendment's protection of freedom of religion and the Fifth Amendment's due process clause. It also argues the order violates the Immigration and Nationality Act by discriminating on the basis of nationality.
The amicus argues that while the law may have been written to appear neutral, its intent was to discriminate against Muslims, an argument that has been made in other court filings as well, often citing Trump and his surrogates' own comments leading up to the signing of the order.
The order "is vastly overbroad -- targeting both individuals and countries in a way that does nothing to further the order's stated purpose of 'protect[ing] the American people from terrorist attacks by foreign nationals admitted to the United States.'" the brief states. "The upshot is that the order does exactly the opposite of what it intends—undermining, rather than enhancing, the nation's security."
Trump has defended the ban as necessary for national security, and the administration notes that the seven countries whose nationals were banned under the order were designated as high risk by the Obama administration and Congress. Homeland Security Secretary John Kelly has described the nations as "failed states" where it is near impossible to get information about applicants to come to the US that is adequate enough to vet them.
The White House is keeping its options open regarding the ban. A source familiar with the decision-making told CNN last week that the Justice Department will not immediately appeal the Ninth Circuit's decision to the Supreme Court and is considering rewriting the order.