Okay kiddo, let me tell you a story about something called ex parte Quirin. During World War II, some German soldiers snuck into the United States by boat. They wanted to do sneaky spy stuff and be all sneaky like spies do. But the United States was like "uh uh, not today" and caught them.
Now, these German soldiers didn't think it was fair that they were being held in jail without a trial. So, they went to court asking for a trial. But the government said they didn't have to give them a trial because they were in the United States when they were caught and they were trying to do sneaky spy stuff, which is really bad.
The government said that these German soldiers were like enemy soldiers attacking the United States during war time. And just like how soldiers don't get a trial when they're captured in a war, these German soldiers didn't get a trial either.
So, the court agreed with the government and said that these German soldiers didn't get a trial because they were like enemy soldiers. This was called ex parte Quirin.
Basically, ex parte Quirin is a rule that says if you're an enemy during war time and you try to do sneaky spy stuff in the United States, you might not get a trial if you get caught.