It is Latin, though apparently dog-Latin. It is obviously playing with the well-known Latin tag "In vino veritas", meaning "In wine [is] truth", in other words that drinking alcohol brings out the truth, leads people to speak the truth.

It is dog-Latin because "in" should be followed by the ablative in Latin (as in "vino"). "Somnifera", from "somnifer" (sleep-inducing, lilterally bringing sleep), could be interpreted as a feminine singular in the ablative (referring to something of feminine gender that induces sleep), but it is almost certainly intended to be a neuter plural, "somnifera" ("things that induce sleep"), of which the singular would be "somniferum", in which case the correct form here would be "in somniferis".

"Things that induce sleep", that is, substances that make you sleep. are properly called "hypnotics" in English. It might just be referring to sleeping pills. However, given the implicit allusion to the wine tag, I think it's more likely that it refers to narcotics, the original meaning of "narcotic" being "sleep-inducing".

The Latin scientific name of the opium poppy is Papaver somniferum".

"Aequitas" is justice in the sense of "equity" or "fairness".