Got a question that maybe deserves a discussion. The police seems to be able to detain you for up to 48 hours in most states without charging you and can release you at any point up to then with seemingly little consequence unless it was a flagrant violation. The standard for stopping someone is reasonably articulable suspicion, IIRC, and I think that applies to immigration detentions.. I'm unsure when probable cause kicks in with immigration. I'm a little concerned because I read about US citizens detained and not let out in the 48 hour period. I'm concerned that the administration may not be too concerned about unlawful detention.

If you read the complaint discussed in the link upthread (repeated below), it's got a nice summary of what the ACLU believes is required.

I think it might be helpful to think of detention in the criminal proceedings as involving two different steps. There's the standard for arresting you, which requires probable cause. Then there's the standard for pre-trial detention - keeping you locked up until there's actually a judicial determination that you're guilty of the crime.

So in order to arrest you, the LEO needs either a warrant (where a judge determines probable cause) or the LEO needs to themselves possess probable cause to arrest you (ie. if they've actually seen you commit the crime). There are exceptions, caveats, etc. "Stopping someone" under a Terry stop has a lower standard (reasonable articulable suspicion, as you point out) - but that's only for a few moments. They can't lock you up for 48 hours without probable cause.

Pre-trial detention has a higher standard. The presumption is that you can't be punished unless you've been convicted of a crime, so the government has to demonstrate that there's some compelling reason for locking you up before that adjudication has been made. Generally that's when you pose either a flight risk or danger to the community, though there are exceptions and caveats, etc.

Immigration involves civil detention, not criminal detention. Congress has passed some provisions of the Immigration and Naturalization Act that govern the potential release of civil detainees. The BIA decision discussed in the ACLU complaint runs through some of the statutory language involved. The DOJ has determined that Congress has not provided for pre-trial release for many (most?) civil detainees under the INA, and (presumably) that this is okay under the Constitution because this is a civil (not criminal) process. I say presumably, because I don't believe it was actually raised in the BIA case. The ACLU is arguing that this violates the constitution - that civil detainees (like criminal arrestees) must be provided pre-trial release absent some reason not to provide it.

aclu.org - New class action lawsuit challenges widespread denial of due process in immigration courts