Trump Officials Say Deportees Were Gang Members. So Far, Few Details.

Families and immigration lawyers argue not all of the deportees sent to a prison in El Salvador over the weekend had ties to gangs.

In the days since the federal government sent hundreds of Venezuelan immigrants to a prison in El Salvador, Washington has been debating whether the White House did indeed defy a federal judge who ordered the deportation flights to turn around and head back to the United States.

But beyond the Trump administration’s evident animus for the judge and the court, more basic questions remain unsettled and largely unanswered: Were the men who were expelled to El Salvador in fact all gang members, as the United States asserts, and how did the authorities make that determination about each of the roughly 200 people who were spirited out of the country even as a federal judge was weighing their fate?

The Trump White House has said that most of the immigrants deported were members of the Venezuelan gang Tren de Aragua, which, like many transnational criminal organizations, has a presence in the United States. Amid the record numbers of migrants arriving at the southern border in recent years, the gang’s presence in some American cities became a rallying cry for Donald J. Trump as he campaigned to return to the White House, claiming immigrants were invading the country.

After Mr. Trump returned to power in January, Tren de Aragua remained a regular talking point for him and his immigration advisers, and the deportation flights last week were the administration’s most significant move yet to make good on its promise to go after the gang. But officials have disclosed little about how the men were identified as gang members and what due process, if any, they were accorded before being placed on flights to El Salvador, where the authoritarian government, allied with Mr. Trump, has agreed to hold the prisoners in exchange for a multimillion-dollar payment.

The Justice Department refused to answer basic inquiries on Monday about the deportations from the federal judge in Washington, D.C., who had ordered the deportation flight to return to the United States. On Tuesday afternoon, he ordered the Justice Department to submit a sealed filing by noon on Wednesday detailing the times at which the planes had taken off, left American airspace and ultimately landed in El Salvador.

More than half of the immigrants deported over the weekend were removed using an obscure authority known as the Alien Enemies Act of 1798, which the Trump administration says it has invoked to deport suspected Venezuelan gang members age 14 or older with little to no due process. The rarely invoked law grants the president broad authority to remove from the United States citizens of foreign countries whom he defines as “alien enemies,” in cases of war or invasion.