Although Lavan was a terrible person, many Rishonim and Acharonim believe that we can learn at least one Halacha from him. In this week’s Parsha, Lavan tricks Yaakov into marrying Leah. When Yaakov asks why he was given Leah instead of Rachel, Lavan explains himself by saying (29:26), “It is not done in our place, to give the younger before the older.” This idea is quoted in a case presented by Tosafot in the Gemara (Kiddushin 52a). A son of R’ Oshiya HaLevi was MeKadesh a daughter of a wealthy man, but did not specify which daughter he was engaging. Rabbeinu Tam rules that the older daughter was engaged, because it is the practice not to give the younger daughter before the older. The Rambam states in Sefer HaMitzvot that the Halacha requiring a younger sibling to respect his or her older sibling is derived from the Mitzvah of respecting one’s parent, because a parent wants a younger child to respect an older child. The younger child indirectly respects his or her parent by respecting the older sibling. This is also relevant to our case. It is respectful to the parents to allow the older child to marry before the younger child.
This is not the only Halacha that Chazal learn from Lavan. They also learn, “Ein MeArvin Simchah BeSimchah,” “one does not mix festivities together.” Lavan tells Yaakov that he will give him Rachel a week later, giving a full week to separate the marriage of Leah and the marriage of Rachel. From this we learn that celebrations should be separated.
From these Halachot, we see that no matter how bad a person may be, there is always something good that can be learned from him.