Sheitel

That a married Jewish woman covers her hair in public is common ground across Orthodoxy. What satisfies the obligation is not, and the disagreement is genuine, sourced on both sides, and does not run along a scale from lenient to strict.

The case for the wig. A sheitel covers the woman's own hair completely, which is what the obligation requires. It is durable, it does not slip, and it allows a woman to meet the requirement without being marked out in a workplace or a street. Ashkenazi authorities from the eighteenth century onward permitted it, and in much of the Ashkenazi world it became the norm.

The case against it. A covering indistinguishable from uncovered hair defeats the purpose of covering. If the point is that a married woman's hair is not on display, a wig that looks like better hair than she had achieves the opposite. Most Sephardi authorities take this view, as do parts of the Hasidic world, and their communities use a scarf, or a scarf over a partial wig, or in some Hasidic groups a scarf over a shaved head.

Reading these as degrees of observance gets it backwards. They are different answers to the same question, and which one a woman follows generally indicates whose rulings her community accepts.

The hair itself

A separate problem attaches to supply. A great deal of human hair for wigs has come from South Indian temples, where devotees offer their hair in tonsure and the temples sell it. In 2004 several Israeli authorities ruled that such hair might constitute benefit derived from idolatrous worship, which would make it forbidden. Sheitels were burned publicly, and a market of some size was disrupted for months.

The ruling was not universally accepted, others held that the tonsure is an offering of the hair rather than to an idol, and that the sale is a subsequent commercial act, and the sourcing question has never fully gone away. It is a good illustration of how far the practical consequences of a halakhic question can reach, and of how tangled two unrelated religions can become through a supply chain neither chose.

In 2004 a large part of the Orthodox sheitel market collapsed within weeks, and the reason was a question about where the hair came from.

Much of the human hair used in high quality wigs was sourced from India, and a substantial part of the Indian supply comes from temple tonsure, where pilgrims shave their heads as an offering, most famously at Tirumala Tirupati. The temples sell the hair at auction, and it enters the international trade.

The halakhic question is whether hair given as an offering at a temple to another deity counts as an object of avodah zarah, idolatrous worship, from which no benefit may be derived. Several senior authorities in Israel, including Rabbi Yosef Shalom Elyashiv, ruled that it did. The consequence was immediate: women were instructed not to wear wigs of uncertain provenance, wigs were destroyed publicly in Brooklyn and in Bnei Brak, prices for European and synthetic hair rose sharply, and a certification system for wig provenance came into being that still operates.

Other authorities disagreed, arguing that the tonsure is a hygienic and votive act rather than an offering to an image, or that the hair is not the object of worship, or that the chain of commerce interposes enough steps. The dispute has not been resolved so much as absorbed into a market where certified non Indian hair is now standard at the strict end.

The episode sits alongside the older objection to the sheitel itself, made by some Sephardi authorities and by figures including Rabbi Ovadia Yosef, that a covering indistinguishable from uncovered hair does not achieve what covering is for. Communities that take that position prefer a scarf, and the two objections come from opposite directions.