Earlier this week, New York Democratic Sen. Kirsten Gillibrand joined with a Republican counterpart, Maine’s Susan Collins, to introduce an amendment designed to reverse President Donald Trump’s controversial ban on transgender service people.

“Any individual who wants to join our military and meets the standards should be allowed to serve, period. Gender identity should have nothing to do with it,” Gillibrand said in a statement.

The showdown between Congress and Trump over the trans ban is starting to mirror the dynamics between Congress and Bill Clinton when the “don’t ask, don’t tell” policy was implemented in 1994. Clinton initially wanted to lift the ban on gay troops entirely, but Congress and the military brass resisted. The result was DADT, a compromise that allowed gay troops to serve as long as they concealed their homosexuality.

Advocates for DADT made a simple and blunt argument: Allowing gay troops to serve openly would hurt morale, hurt the cohesion of individual units, and ultimately weaken the military’s ability to fight and win wars.

More than 23 years after DADT was implemented, we know that almost all of the concerns about gay troops openly serving were misguided. The RAND Corporation, a global nonprofit think tank, studied the impact of DADT as well as the consequences of its repeal in 2010 and found that military preparedness was not meaningfully harmed by allowing gay troops to serve openly.

In July 2016, RAND released a similar report about the implications of allowing transgender troops to serve openly in the military, which found that the cost of gender-transition related health care was relatively low, that force readiness would be minimally impacted, and that lifting the ban on trans troops would benefit all servicemembers.

I spoke with Agnes Schaefer, who co-authored both studies, about their findings. I wanted to know what the military learned from its experiment with DADT and what potential problems — for trans troops and the Pentagon — could arise if the Defense Department carries out Trump’s ban on transgender troops.

“The major concern now,” she told me, “is what do you do with the people who are already serving, who have put themselves on the line by self-identifying as transgender because they were told that it was okay to do so? They stood up and waved their hands and now they’re potential targets.”

Our full conversation, lightly edited for clarity, appears below.

Sean Illing

You studied the design and implementation of “don’t ask, don’t tell” closely. How problematic was that policy?

Agnes Schaefer

Bill Clinton initially wanted to lift the ban on gay troops openly serving altogether. Like Trump, however, he didn't have the support in Congress to do what he wanted, so the compromise was DADT. The problem with that is it created a lot of ambiguity in terms of the implementation process — no one really understood how it would work. There were all these unanswered questions: On what basis would you discharge someone? Could you do it on hearsay? Could you kick someone out if they were seen walking down the streets holding hands or kissing? None of this was clear.

Sean Illing

It’s interesting to me that the military brass was opposed to “don’t ask, don’t tell” in 1994 and it’s opposed to Trump’s trans ban now, even though the policies are moving in opposite directions.

Agnes Schaefer

That’s right, and it’s important to clarify that the military chiefs of every branch of service supported the Obama administration’s lifting of the trans ban last year — every single one of them.

Sean Illing

And that’s in part because of what you found when you researched the implications of lifting the ban, right?

Agnes Schaefer

When Obama decided that he was going to potentially lift this ban on transgender service members we were asked by the Pentagon’s undersecretary of defense for personnel and readiness to again look at the potential implications of lifting that ban. We weren’t asked to make recommendations — only to assess the implications. They wanted to know how this might impact unit cohesion and military readiness. Our conclusion was that lifting the ban would have a minimal impact.

“These questions about gender identity and sexuality simply aren’t major concerns for people actually serving”

Sean Illing

I’m struggling to square your research with the justifications the Trump administration is offering in defense of its proposal to reimpose the ban on trans troops. They seem to think banning trans troops will save a lot of money on health care and improve military readiness, but your organization has studied this rigorously and found the opposite.

Agnes Schaefer

In terms of costs, we found that if DOD was to extend health care coverage for gender-related transition treatments, it would cost between $2.4 and $8.4 million per year. That represents a maximum of 0.134% of the $6 billion active component health care budget. So we're talking about small numbers.

We also looked at the impact on military readiness, because we weren’t sure. First of all, we don't know what the number of transgender individuals are in the military, because at the time we did our study, they would be discharged if they self-identified. So we looked at the best available data in the civilian population and then we applied those to the military and made several adjustments based on male-female ratio and things like that.

What we found was that when you take a look at the types of treatments, the number of people that transition, and the number of people that choose to have these surgical treatments, when you take a look at all that and then factor in recovery times for those types of treatments, that would lead to a loss of less than 0.0015% of total available labor years in the active component. So again, we’re talking about a very minimal impact.

Sean Illing

I served when DADT was still official policy and the attitude among the people I worked with was mostly indifference. People thought it was silly. No one gave a damn if someone was gay so long as they did their job. But the trans ban will create a situation of limbo for troops that seems far worse. With DADT, soldiers were asked to conceal their identity. In this case, they were told it was okay to reveal their identity and now they’re facing punishment.

Agnes Schaefer

You hit on a crucial point. The big issue is how they're going to deal with folks that are currently serving that are transgender. Some in the media have talked about how this is no longer allowing transgender individuals to enter the military, but they never were allowed to enter.

What happened was, when they decided to lift the ban last June, as part of their implementation timeline, they were going to spend the first year trying to sort out everything for those who are currently serving. They wanted to figure out all the systems so that somebody could change their gender in the personnel systems and things like that. Then they were going to set a target date for allowing new transgender recruits for July of this year. But Secretary James Mattis said that we needed more time, perhaps as much as two years, to get everything right.

The major concern now is, what do you do with the people who are already serving, who have put themselves on the line by self-identifying as transgender because they were told that it was okay to do so? They stood up and waved their hands and now they’re potential targets.

“Much of the initial DADT debate was about social cohesion and whether that would break down if gay troops could serve openly, but we now know that that’s not true“

Sean Illing

What did we learn from the “don’t ask, don’t tell” experiment, and how might those lessons apply to the proposed trans ban?

Agnes Schaefer

There were concerns in some of the services when the Obama administration talked about lifting the ban. The biggest concern was unit cohesion and unit readiness. But we found in our studies of DADT and of integrating women into various military roles that there’s two elements of cohesion: social and task-oriented. Social cohesion is about how much you like the people you work with, and task cohesion is about how well people do their jobs.

The big takeaway from our research, and you alluded to this a minute ago, is that people may not like everyone they work with, but all that matters is that they’re able to get the job done. In the military especially, that’s how you earn the respect of fellow soldiers. That’s how they know you have their back.

Much of the initial DADT debate was about social cohesion and whether that would break down if gay troops could serve openly, but we now know that that’s not true. The trans ban debate began as a debate about cost and readiness, but there really isn’t much evidence to support those concerns.

Sean Illing

And you’ve studies how other countries have opened up their militaries to gay and transgender troops. Does their experience align with your findings here?

Agnes Schaefer

Yes. We looked at 18 countries and we found no evidence that cohesion, readiness, or operational effectiveness were negatively affected by allowing transgender individuals to serve openly — and that again reinforces the findings from the DADT experience. These questions about gender identity and sexuality simply aren’t major concerns for people actually serving.

Again, it’s about one thing: Can you do your job?