A subpoena is a court order, therefore, if you fail to show up, then the court could find you in contempt and issue a bench warrant for your arrest.
Generally, you must testify as the court orders. However, every person has the Fifth Amendment constitutional right against self-incrimination. If there is any possibility that you will be asked a question where a truthful answer might later be used to try to link you to a crime, then you should excused by the judge. Some judges will excuse a witness entirely, while others will only prohibit certain questions from being asked. It is important to schedule a free consultation with a criminal lawyer buffalo ny who understands the area of law and how it applies to the facts in your case.
Again, the most important thing is that you need to show up because a subpoena is a court order, even if signed by an attorney or court clerk instead of a judge.
If you violate a court order to appear, the court may find you in contempt of court. In some cases, it could be worse. Furthermore, keep in mind, if you are ever arrested for anything in the future, the fact that you were found in contempt could be used by the prosecution to set a high bond or deny bond entirely.