This is a question specific to the US.
In the US, we're required to serve jury duty once a year when we get a jury summons. Recently (or at least for me), instead of waiting at the courthouse all day, we can wait at home and be "on-call" and call the courthouse at a specified time to see if we need to go in. I didn't have to so I went to work.

One of my co-workers ran into me and asked why I was in the office since I had jury duty. I explained the same situation as I did above. She said I didn't have to go in since I had jury duty, even if I was dismissed early due to the courthouse not having a case for us to try.

Is this true? Even if we get dismissed early b/c there's no case to try, we don't have to go into the office afterwards?

Thanks in advance for your help/reply.

EDIT/CLARIFICATION: The day I'm supposed to report to the courthouse, I was told to call the courthouse at 12pm to see if I need to come in. The message said I didn't need to come in so I went to work afterwards.

Thanks for the comments/answers, I'll ask HR to see what they say but I also wanted to see what others have to say or see what other ppl know or have experienced.