term:

Attack

attack n

: an attempt to prove something invalid or incorrect esp. through judicial procedures [made an on the will as not properly witnessed]
;specif
: an attempt to have the judgment of a court corrected or overruled

collateral attack
: an attack on a judgment made during or by a proceeding brought for a different purpose see also habeas corpus ad subjiciendum at habeas corpus

direct attack
: an attack on a judgment made in a proceeding (as an appeal) brought for the specific purpose of having the judgment corrected or overturned
attack vb

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