  We investigate the leading power corrections to the decay rates and
distributions in the decay $B \rightarrow X_s \ell^+ \ell^- $ in the standard
model (SM) using heavy quark expansion (HQE) in $(1/m_b)$ and a
phenomenological model implementing the Fermi motion effects of the b quark
bound in the B hadron. In the HQE method, we find that including the leading
power corrections the decay width decreases by about 4% and the branching ratio
by about 1.5% from their (respective) parton model values. The dilepton
invariant mass spectrum is found to be stable against power corrections over a
good part of this spectrum. However, near the high-mass end-point this
distribution becomes negative with the current value of the non-perturbative
parameter $\lambda_2$ (the $\lambda_1$-dependent corrections are found to be
inoccouos), implying the breakdown of the HQE method in this region. Our
results are at variance with the existing ones in the literature in both the
decay rate and the invariant dilepton mass distribution calculated in the HQE
approach. As an alternative, we implement the non-perturbative effects in the
decay $B \rightarrow X_s \ell^+ \ell^- $ using a phenomenologically motivated
Gaussian Fermi motion model. We find small corrections to the branching ratio,
but the non-perturbative effects are perceptible in both the dilepton mass
distribution and the Forward-Backward asymmetry in the high dilepton mass
region. Using this model for estimating the non-perturbative effects, we
present the decay rates and distributions for the inclusive process $B
\rightarrow X_s \ell^+ \ell^- $ in the SM.
