0 past simple and past participle of subpoena
1 to order someone to go to a law court to answer questions:
A friend of the victim was subpoenaed as a witness by lawyers representing the accused.
[ + to infinitive ] They were subpoenaed to testify before the judge.
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.