Sen. Kirsten Gillibrand (D., N.Y.) introduced a bill last Thursday that would oblige immigration enforcement agents to routinely report stops and searches, even if they did not lead to arrests.

The Department of Homeland Security Accountability and Transparency Act (DATA Act) would introduce a reporting requirement for the searches that Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE) agents routinely conduct on buses and trains. The proposal is backed by several of Gillibrand's Democratic colleagues, including Sens. Elizabeth Warren (Mass.), Tom Udall (N.M.), and Jeff Merkley (Ore.).

CBP and ICE have expansive search powers, which critics suggest contravene Fourth Amendment protections. Under federal law, searches conducted by CBP and ICE at entry ports can be carried out without a warrant or reasonable suspicion. Indeed, some but not all of these expansive search powers extend to any place within 100 miles of any U.S. "external boundary." The ACLU estimates that around two thirds of the U.S. population lives within the covered area.

These expansive powers come with minimal transparency, according to Gillibrand's office: Agents are not required to keep records of stops or searches unless they lead to arrest or use of force. That lack of data means that it is hard, for example, to determine the number of searches and stops conducted by CBP/ICE. For comparison, the state-level policies for searches by police officers are mixed: a Stanford project on police traffic stops and searches was able to obtain at least some information from 31 states.

The DATA Act would compel CBP and ICE agents to begin reporting data from patrol stops, secondary inspections, or searches at a "non-international port of entry checkpoint." The information required would include identifying data on the person detained, the basis for the stop, whether or not force was used or a person was arrested, and the date, time, and location of the stop. CBP would additionally be obliged to submit data on temporary and permanent checkpoints assembled by CBP officers.

All of this, Gillibrand said, was in the name of securing privacy and due process rights.

"Keeping our country safe cannot come at a cost to basic human rights. When border patrol agents stop and question people in New York and in many places across the country, they aren't keeping data about why they targeted a particular person or what happened during their encounter," she said.

It is unclear whether the bill will go past the proposal stage, or what impact it would have on immigration enforcement efforts if passed. The Department of Homeland Security, CBP, and ICE all declined to comment on it, and representatives from the respective unions for ICE and CBP did not return requests for comment.

Such enforcement is an increasing challenge for agencies like CBP and ICE. Attempted entries along the southwestern border rose 300 percent in April as compared against the same month last year, prompting even further tightening of the Trump administration's already tightened immigration policy. President Donald Trump has expressed his dissatisfaction with the insufficiency of efforts to curb illegal immigration, with multiple outlets reporting that he tore into Secretary of Homeland Security Kirstjen Nielsen at a recent cabinet meeting over the issue.