term:

Underinclusive

underinclusive adj

: not sufficiently inclusive
: excluding something that should be included
;specif
: not affecting others similarly situated with respect to the purpose of the law and esp. in violation of equal protection [an classification] [all four ordinances are overbroad or in substantial respects "Church of the Lukumi Babalu Aye v. City of Hialeah, 508 U.S. 520 (1993)"] compare overinclusive
un·der·in·clu·sive·ness n

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