There is a long-standing dispute in the ultra-Orthodox community about whether married women may wear wigs instead of other head coverings. Those who support the wearing of wigs claim that while Jewish law demands that the head be covered, the type of covering does not matter. Opponents of this view claim that if the head covering looks like hair, then it is pointless. An announcement by the Institute posted in synagogues around the country prior to Shavuot states definitively that wigs are forbidden.
Citing decisions in Jewish law that forbid the wearing of wigs that look like hair, by among others, Rabbi Shmuel Auerbach, Rabbi Shalom Elyashiv, and Rabbi Nissim Karelitz, three of the most important ultra-Orthodox authorities on Jewish law.
“Modern wigs are forbidden according to the Torah since they are just as much a breach of the law as hair, if not more,” according to the announcement. “Unfortunately, such breaches are rampant among the ultra-Orthodox, and everyone has an obligation to put out the burning flame and to make haste to remove an obstacle, to eradicate this terrible problem of wigs… Every woman well knows in her heart the bitter truth, and how wigs look today, and she is going to be judged for this, and no excuses will avail in the next world.
"Therefore, every woman should make haste to join the thousands of righteous women who have already removed all kinds of wigs and pieces of wig that harm the souls of pure and holy young men and yeshiva students of the Jewish people.”
"Forbidden according to the Torah"
According to the announcement, while there were a number of authorities in Jewish law who permitted the wearing of wigs for married women, they were referring to the older type of wig. The newer wigs, which look just like real hair, are clearly “forbidden according to the Torah.”
Furthermore, the Institute’s instructions for those who have gone back to wearing an acceptable head covering are to cover the head with a “modest kerchief, and not, Heaven forbid, all kinds of newfangled modern kerchiefs and head coverings that are liable to attract attention because of the evil inclination and to cause the public to sin with accessories that attract the eye.”