Why does the Torah incorporate a prohibition against giving rulings after drinking wine?
Seforno: Because wine captivates a person's heart, causing him to forget. 1
QUESTIONS ON RASHI
Rashi writes that a Chacham who gives rulings after drinking wine is not Chayav Misah. What is the reason? This was taught together with entering the Mikdash after drinking, for which there is Misah!
Rashi: Because, with reference to the Kohanim, the Torah writes in Bamidbar 18:1 "Atah u'Vanecha Itach ... v'Lo Samusu", to preclude a Rav from Misah.