marco100 wrote "None of the people being detained claim to be in the United States legally."

Actually, several say they were following the law, and their lawyers agree. Denying military spouses' legal applications for green cards is bizarre behavior.

I suppose a possible explanation for denying legal applications for green cards is incompetence, ignorance, or just plain stupidity. Or maybe White Supremacy or Christian Nation ideologies are being enforced, with the applicants being rejected for some sort of belief litmus test. Or maybe poor management has offered bonuses for bad behavior. Strange.

"There are various exceptions to a visa overstay that you should be aware of. One exception is a provision in the U.S. law that allows immediate relatives of U.S. citizens to be exempt from the visa overstay. However, this exemption only applies to:
Spouses
Parents
Unmarried children (under the age of 21)

However, in order to be eligible for this exemption and for adjustment of status (meaning they can get a green card in the U.S.), the immediate relative must have a lawful entry into the U.S. If someone entered the country without going through a CBP officer, they will not be able to submit a green card application."
jlkattorneys.com - Are there any exceptions to a visa overstay