  In this paper, we examine observational constraints on the power law
cosmology; essentially dependent on two parameters $H_0$ (Hubble constant) and
$q$ (deceleration parameter). We investigate the constraints on these
parameters using the latest 28 points of H(z) data and 580 points of Union2.1
compilation data and, compare the results with the results of $\Lambda$CDM. We
also forecast constraints using a simulated data set for the future JDEM,
supernovae survey. Our studies give better insight into power law cosmology
than the earlier done analysis by Kumar [arXiv:1109.6924] indicating it tuning
well with Union2.1 compilation data but not with H(z) data. However, the
constraints obtained on $<H_0>$ and $<q>$ i.e. $H_0$ average and $q$ average
using the simulated data set for the future JDEM, supernovae survey are found
to be inconsistent with the values obtained from the H(z) and Union2.1
compilation data. We also perform the statefinder analysis and find that the
power-law cosmological models approach the standard $\Lambda$CDM model as
$q\rightarrow -1$. Finally, we observe that although the power law cosmology
explains several prominent features of evolution of the Universe, it fails in
details.
