term:

Compulsory

compulsory adj

1 : required or compelled by law
: mandatory obligatory [ arbitration] [ insurance]
;specif
: required to be brought or asserted in a pleading because of having arisen from the transaction or occurrence that is the subject of litigation [a counterclaim] [ reconvention] compare elective, permissive
2 : using compulsion
: compelling [ measures]
com·pul·so·ri·ly [-sə-rə-lē]
adv

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.