This case has been decided!
Noncitizens may be detained for lengthy periods of time while they await a decision on deportation. Alejandro Rodriguez, a Mexican citizen and lawful permanent resident, was arrested in 2004 for a drug offense and vehicle theft. His immigration proceedings determined he would be removed. He appealed the removal, and the appeal took a while. In 2007, Rodriguez filed a petition arguing he should not be left in jail for that long. He came to represent a class of similarly-situated noncitizens in this case.
In Jennings v. Rodriguez, the Court will be deciding if noncitizen detainees should be entitled a bond hearing if they are detained for lengthy periods.
Here is our graphic explainer of the legal issues. For more information and additional facts of the case, see this SCOTUSblog report.