Words from the Canadian Law Dictionary

Its useful to know what words mean when they are used in important situation. Having a dictionary that explains those words can really help. 

An important word to learn is "subpeona"
from reading the Canadian Law Dictionary (the reference for Canadian lawyers and courts), one can surmise that the action required by receiving a subpoena is voluntary.
Please look at the following pages to come to your conclusion:
Page 1 ; Subpoena
... to compel the appearance of a witness... 
Page 2 ; Appearance
... the voluntary submitting of oneself to ....