Once upon a time, there was a book called "Ulysses". Some people thought there were some bad words and inappropriate things in it. In fact, some people were so upset about it that they took the people who published the book to court - that's when a judge decides if someone broke the rules or not.
The trial happened because some of the words in the book were not allowed to be said or written at that time. These words were considered "obscene" which means they were really inappropriate and people didn't want them to be used.
The people who published the book, the Little Review, were in trouble because they had printed parts of the book with these bad words in it. The publishers argued that they were just trying to share important literary works, but the people accusing them said that they were breaking the law.
The trial ended up being really lengthy and complicated because there were a lot of different arguments being made about what was okay to print and what wasn't. Some people thought the book was a work of art and should be allowed to be shared no matter what, while others thought it was just plain dirty and shouldn't be allowed at all.
In the end, the publishers were found guilty and they had to pay a fine. But the trial ended up being a really important moment in history because it started a conversation about what we consider to be obscene and what we should be allowed to read and share.