  Chemical disequilibrium has recently become a relevant topic in the study of
the atmospheres of of transiting extrasolar planets, brown dwarfs, and directly
imaged exoplanets. We present a new way of assessing whether or not a
Jovian-like atmosphere is in chemical disequilibrium from observations of
detectable or inferred gases such as H$_2$O, CH$_4$, CO, and H$_2$. Our
hypothesis, based on previous kinetic modeling studies, is that cooler
atmospheres will show stronger signs of disequilibrium than hotter atmospheres.
We verify this with chemistry-transport models and show that planets with
temperatures less than $\sim$1200 K are likely to show the strongest signs of
disequilibrium due to the vertical quenching of CO, and that our new approach
is able to capture this process. We also find that in certain instances a
planetary composition may appear in equilibrium when it actually is not due to
the degeneracy in the shape of the vertical mixing ratio profiles. We determine
the state of disequilibrium in eight exoplanets using the results from
secondary eclipse temperature and abundance retrievals. We find that all of the
planets in our sample are consistent with thermochemical equilibrium to within
3-sigma. Future observations are needed to further constrain the abundances in
order to definitively identify disequilibrium in exoplanet atmospheres.
