  The energy conditions give upper bounds on the luminosity distance. We apply
these upper bounds to the 192 essence supernova Ia data to show that the
Universe had experienced accelerated expansion. This conclusion is drawn
directly from the distance modulus-reshift graph. In addition to be a very
simple method, this method is also totally independent of any cosmological
model. From the degeneracy of the distance modulus at low redshift, we argue
that the choice of $w_0$ for probing the property of dark energy is misleading.
One explicit example is used to support this argument.
