Okay kiddo, so there was something called United States v. Graham. That's when some people were accused of doing bad things with their phones. But it wasn't just regular bad things like using them too much or dropping them. They were accused of using their phones to do really bad things like pretend to be someone else and steal stuff.
So, the people who were accused said that the government shouldn't be able to look at their phone records. But the government said that they could because it helped them catch the bad guys.
The case went all the way to the big bosses of the court system, the Supreme Court. And the Supreme Court said that the government could look at the phone records because it was important for catching bad guys and keeping everybody safe.
So now, if the government thinks someone is doing something really bad with their phone, they can look at their phone records to try and catch them. But they have to follow rules and get permission first.