  We propose a new set of observables that can be used as experimental null
tests of the Standard Model in charged and neutral B decays. The CP asymmetries
in hadronic decays of charged B mesons into inclusive final states containing
at least one of the following mesons: K_{S,L}, eta', c\bar c bound states or
neutral K^* or D mesons, for all of which a U-spin rotation is equivalent to a
CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin
limit. We show how this reduces the theoretical error by using Soft Collinear
Effective Theory to calculate the CP asymmetries for K_{S,L} X_{s+d}, K^*
X_{s+d} and eta' X_{s+d} final states in the endpoint region. For these CP
asymmetries only the flavor and not the charge of the decaying B meson needs to
be tagged up to corrections of NLO in 1/m_b, making the measurements more
accessible experimentally.
