term:

Abatement

abatement n

1 : the act or process of abating or the state of being abated [challenged the of her bequest] [ of a private nuisance by self-help “W. L. Prosser and W. P. Keeton”]
2 : an amount abated
: deduction
;esp
: a deduction from the full amount of a tax

in abatement
: subject to termination because of a formal or procedural defect [there shall be no reversal in the Supreme Court…for error in ruling upon matters in abatement “U.S. Code“]