Two years ago, President Obama tried to fix what he called a "broken" immigration system: he offered amnesty to five million undocumented immigrants in the U.S.
The deal granted temporary legal status and work permits for some, put a stop to deportation orders for others and more.
Today, that executive action faces a direct challenge in the U.S Supreme Court.
For a refresher on what's at stake, and what might happen, Take Two chats with Niels Frenzen, clinical professor of law and director of the Immigration Clinic at USC.