Belsky served as a member of the Iggud HaRabbonim[5] beth din (religious court) under Yitzchok Isaac Liebes, Baruch Leizerowski and Herschel Kurzrock.

[6] Some events that he addressed with this beth din were: the aftermath of the September 11 attacks and freeing its widows from agunah status; New York City tap water;[7] human-hair wigs from India;[8] surrogate motherhood; and a kashrut scandal in Monsey.

Belsky's first kashrut position was with the Kof-K.[9] In 1987, he transferred to the Orthodox Union (OU), eventually being described as one of their "chief experts",[10] and ultimately served in that capacity for more than 28 years.

[6] Belsky publicly defended confessed sexual abuser Yosef Kolko, who taught children at a Lakewood, New Jersey, yeshiva.

[14] According to The Jewish Week, the Ocean County, New Jersey District Attorney privately warned Belsky to cease and desist writing letters defending Kolko, or risk prosecution.

[18] In a 2011 interview with The New York Times about a divorce case, Belsky described a court-ordered child custody order as "a joke" since it interfered with observance of the Jewish Sabbath.