Soontobedivorce said:
you will be in contempt of court so it would be good idea to show up. If you live a couple hours away, you can request court to pay you for transportation costs if you are a witness to something.
My response:
The above is a bunch of bullsh%t.
Obviously, "Soontobedivorce" has never heard of the word "Jurisdiction".
Unless the subpoena was issued through your State court, you don't have to appear on the subpoena. Now, it's true that when you drive in another State, you impliedly agree to all of their laws. However, once you leave, jurisdictional "States Rights" take effect and one State has no power over the citizen of another State without the home State's "permission"; i.e., the issuing State needs to ask for, and obtain, your State's "permission" to make the subpoena enforceable.
Now, lets look at this matter from a pragmatic point of view. If you don't appear, then the truck driver is going to "get away" from his just punishment and the case against him will be dismissed.
So, you can "stand" on jurisdictional grounds IF your State didn't issue the subpoena, or you can attend voluntarily and see to it that Justice is served. Your choice.
IAAL