When a same-sex American couple recently brought their baby girl, Simone, home for the first time, they did so using a tourist visa for her because she was born in the U.K. Simone was conceived with a British friend’s donor egg and one of the fathers’ sperm, with the help of a surrogate in the U.K.

The new fathers applied for U.S. citizenship for their daughter, never imagining there would be any roadblocks to obtaining that citizenship. Unfortunately, that application was denied. The U.S. State Department reportedly claimed that Simone didn’t meet the requirements of the Department’s policy, which requires that a U.S. citizen be a biological parent of a child born abroad through assisted reproduction.

When a child is conceived using sperm and an egg that did not come from a married couple, the State Department treats the child as one born out of wedlock and imposes stricter requirements to citizenship.

Simone’s fathers, Derek Mize and Jonathan Gregg, along with at least two other same-sex couples, have filed suit against the U.S. Secretary of State, Mike Pompeo, alleging discrimination. The couples claim their applications would have been handled differently had the State Department treated them as married couples.

The couples’ lawyers have argued that the State Department under the Trump administration is not applying an Obama-era policy appropriately. That policy was changed after same-sex marriage was legalized to provide that the biological connection to a child born abroad through surrogacy could come from either parent, essentially treating children like Simone as children born in wedlock.