Democratic leaders came out in force on Wednesday in favor of a proposal to prohibit Americans who are on federal government terrorist watchlists from purchasing firearms. A group of Democratic senators waged a filibuster on the Senate floor. And after presumptive GOP presidential nominee Donald Trump announced that he intends to meet with the powerful National Rifle Association to discuss a similar restriction, presumptive Democratic nominee Hillary Clinton welcomed him to the cause.

For Democrats, however, the move amounts to a strong endorsement of a system that civil liberties advocates have called a “Kafkaesque bureaucracy,” and which some Democrats have previously criticized for being secretive, unaccountable, and discriminatory.

Getting your name on a watchlist is much easier than getting it off. According to interagency watchlisting guidelines The Intercept published in 2014, it takes neither “concrete facts” nor “irrefutable evidence” to add someone’s name as a terror suspect. The guidelines allow the administration to name individuals as representatives of terrorist groups they have no demonstrable connection to and to put entire “categories” of people on the no-fly list.

There was no way for anyone to know ahead of time if they were on the no-fly list until 2014, when a federal court ruled that the government had to inform citizens when they were placed on it. But the Department of Homeland Security still refuses to tell people why, or offer a form of judicial redress.

Before the September 11 attacks, the U.S. government only banned 16 people from flying on planes for their connections to terror groups. During the George W. Bush administration, that number swelled dramatically, leading to some high-profile embarrassments.

In 2004, Sen. Ted Kennedy, D-Mass., told a congressional committee that he had been stopped and questioned at airport security five times because his name appeared on the watchlist. A Bush administration official told the Washington Post anonymously that “T. Kennedy” was a common terrorist alias.

On the same day, former civil rights activist Rep. John Lewis, D.-Ga., announced that he had been “held up” more than 35 times that year while trying to fly.

But placement on a terror watchlist can have far worse consequences than harassment at airport security. Lyman Latin — a disabled U.S. Marine veteran who was wrongly placed on the list and later joined an ACLU lawsuit in response — was unable to get a Veterans Administration disability evaluation completed because he was blocked from flying from Egypt to the United States. As a result, his disability payments were reduced, and he had to move into lower-cost housing, exacerbating the impact of his disability. Another Army veteran represented by the ACLU was stuck in Colombia for years due to his inability to fly home.

Individuals who have been placed on the government’s watchlists have even been subject to extra scrutiny in court for cases completely unrelated to terrorism — as their designation on the watchlist can end up on their rap sheets for judges to see.

“The federal watchlists that the compilers of rap sheets draw on for these notations are notoriously arbitrary and inaccurate. People are placed on these lists without ever being told why or given an opportunity to contest their listing. And the lists appear to focus disproportionately on individuals with Muslim-sounding names,” Ramzi Kassem, an associate professor at CUNY School of Law, told The Intercept in March.

In 2014, the Associated Press reported that more than 1.5 million names have been added to various watchlists in the five years after Umar Farouk Abdulmutallab, colloquially known as “the underwear bomber,” failed to blow up an airplane over Detroit in 2009.

Documents published by The Intercept in 2014 showed that nearly half of the people on the government’s shared list of terror suspects are marked as having “no recognized terrorist group affiliation.”

In April, the Council of American-Islamic Relations in Michigan filed a class action lawsuit alleging that the sweeping watchlist system is arbitrary and discriminatory against Muslims. One of the plaintiffs in the lawsuit was a 7-month-old infant whose mother was stopped at airport security while he was patted down, subjected to “chemical testing,” and had his diapers searched — all because the baby’s boarding pass labeled him a “known or suspected terrorist.”

In the past, some Democrats recognized these problems. Rep. Sheila Jackson Lee, D-Texas, chaired a hearing on the watchlist in 2008, saying that she was “not very happy” with a list that misidentifies individuals “who innocently come to use the airlines and to visit Grandma, to go on a family vacation, to try to make deadlines to a funeral, and whatever else the airlines are used for.” By December of last year, she was pushing the list’s use to bar gun purchases. “We’re just asking for terrorists not to be able to walk into a gun shop and buy a gun,” she said.

“Over the years, this list has grown to have over 1.1 million entries. With so many different names on the list, it is not surprising that every single day countless Americans are misidentified as terrorists,” Rep. Yvette Clark, D-N.Y., said in February 2009. But after the San Bernardino massacre, and when House Republicans blocked action on a bill to bar gun purchases from those on the list this past December, she tweeted out an article about House Democrats excoriating the move.