Olmstead v. United States is a case that happened a long time ago in the United States. It is about a man named Roy Olmstead who was suspected of making and selling alcohol illegally, which was against the law at that time. The police wanted to catch him, so they used a wiretap to listen in on his phone conversations.
A wiretap is like a secret microphone that can hear what people are saying on the phone without them knowing. The police used this wiretap to listen in on Olmstead's conversations and found out that he was selling alcohol illegally.
Olmstead was arrested and put on trial, but he said that the wiretap was illegal because the police did not have a warrant to use it. A warrant is like a permission slip from a judge that says it's okay for the police to do something.
The case went all the way to the Supreme Court, which is like the boss of all the courts in the United States. The Supreme Court had to decide whether the wiretap was okay to use or not.
In the end, the Supreme Court said that the wiretap was okay because it did not physically trespass on Olmstead's property. Trespass means going onto someone else's property without permission. The Supreme Court said that because the wiretap didn't physically go on Olmstead's property, it was okay to use.
This was a big deal because it meant that the police could use wiretaps without a warrant. It also meant that people's privacy was not as protected as they thought it was.