The hidden Jewish law woven into your clothes

Chava Goldberg sat at her sewing desk in Norfolk, Virginia, carefully opening the linings, collars and waistbands of suits, hats and dresses brought by clients in the weeks before Rosh Hashanah. She searched each piece for shatnez, the mixture of sheep's wool and linen that Leviticus 19:19 and Deuteronomy 22:11 forbid in a single garment. Goldberg, an interior designer by training, is one of roughly 200 to 250 people worldwide qualified to perform the inspection. The rule forms one of the 613 commandments in the Torah, alongside the Sabbath and honoring parents, yet its purpose remains unclear outside Orthodox circles. Some connect it to the story of Cain and Abel, whose offerings of flax and wool came from brothers at odds. Maimonides linked the ban to practices of ancient idolatrous priests. Before the Industrial Revolution most cloth was made and sewn locally, often by observant Jews themselves, so few garments required testing. Global production changed that, as manufacturers blend fibers from many sources and use hidden threads in supports and pads. Joseph Rosenberger, an Austrian Holocaust survivor who reached the United States in the 1940s, noticed the shift and opened the first American shatnez laboratory. Rabbi Yosef Sayagh later expanded the work by founding the International Association of Professional Shatnez Labs and training about 250 testers through a 40-hour course in Lakewood, New Jersey, that covers textile science, microscopy and Jewish law. Today roughly 150 testers work in North America. Rabbi Aharon Drebin and others examine up to three dozen internal parts of a suit, from felt under the collar to shoulder pads and waistband canvas, because labels list only the outer fabric. Amy Teifer, who works in New York City's Garment District, studies the same skills while planning her own line of certified garments. The prohibition applies not only to clothing but to any item that touches the body, including rugs, pillows and baseball gloves. Certified testers such as Goldberg spend one to two hours on a suit, though experienced hands finish faster, and they perform the service mainly for the community rather than as a main livelihood. Demand rises each year as more families seek the checks before the Jewish New Year, and the network of laboratories now reaches from Queens and Brooklyn to upper Manhattan and beyond.