Liberal Democrats in Congress are having another go at legislation that would make it difficult if not impossible for the Department of Homeland Security to detain illegal immigrants considered “vulnerable” because they identify as gay or lesbian or don’t speak English.

The bill, the Dignity for Detained Immigrants Act, was re-introduced by Representatives Primila Jayapal and Adam Smith, along with Senator Booker, last week and is co-sponsored by dozens of Democrats in both chambers. It was first introduced in the 117th Congress, in 2021, but never made it out of committee. Its sponsors say the legislation is urgent in light of the approaching end of the Title 42 public health measures that allow the government to swiftly expel illegal immigrants.

“We cannot wait any longer to reform our broken immigration system to ensure it is humane and just,” Mr. Smith said. “The Dignity for Detained Immigrants Act would overhaul our immigration detention system by ending mandatory detention, promoting community-based alternatives, and ending the use of private, for-profit detention centers that have a shameful history of prioritizing their own profits over the civil and human rights of children and families.”

Among other measures, the bill would outlaw mandatory detention of migrants who enter the country illegally and are captured, forbid the detention of families and children, and prevent the department from detaining “vulnerable” immigrants unless it can prove that it’s impossible to find a community-based supervision program. The legislation defines a “vulnerable person” as anyone under the age of 21 or over the age of 60, anyone pregnant or mentally or physically disabled, anyone who identifies as gay, lesbian, bisexual, transgender, queer, or intersex, or anyone with “limited English proficiency.”

Immigrants’ rights groups hailed the measure as a long overdue overhaul of the system deployed by U.S. Immigration and Customs Enforcement to hold illegal immigrants while they are awaiting adjudication of their asylum claims or other court proceedings.

“The U.S. immigration detention system is the largest in the world, depriving tens of thousands of immigrants of their freedom and rights on any given day,” the policy director for Freedom for Immigrants, Andrea Carcomo, said. “Black immigrants and immigrants of color are disproportionately harmed by this intrinsically abusive detention system. … This act will bring us one step closer to realizing an immigration system rooted in racial equity, dignity, and fairness for all people.”

Ms. Jayapal said the bill is all the more urgent given reports that President Biden is considering restarting a Trump-era policy that he reversed only two years ago — the detention of families with children who attempt to enter the country via its southern border without proper documentation. Re-implementing the practice would coincide with the end of the Title 42 on May 11.

Border Patrol officials are said to be expecting a surge of migrants, many of whom have been waiting in makeshift camps just across the border in Mexico, to renew their attempts to enter the country when Title 42 ends. In an address billed as the first “state of homeland security” address last week, the homeland security secretary, Alejandro Mayorkas, said additional measures are being drafted in an effort to curtail the worst crisis in decades at the southern border.

“One cannot deter one’s way through a migration challenge,” Mr. Mayorkas said. “So our model is as follows: Build lawful pathways; cut out the smugglers who exploit these vulnerable individuals; build lawful pathways that give individuals an opportunity to reach the United States safely, in an orderly way to avail themselves of the humanitarian relief our laws provide, and then deliver consequence for those who do not avail themselves of those lawful pathways.”

Republicans in the House of Representatives have been threatening for months to try to impeach Mr. Mayorkas for what they say is his incompetence in the face of the migrant crisis, but the effort has not advanced beyond bombast and heated hearings.

Congresswoman Marjorie Taylor Green stunned her GOP colleagues on the Homeland Security Committee last week when she called Mr. Mayorkas a “liar” in one particularly tense exchange. The chairman of the committee, Mark Green, forbade her from speaking again during the remainder of the hearing and threatened to have her removed from the committee if she repeated her performance.