Are women included in the obligation of Tefilin and Tzitzit?
Although we all know the answer to this question, that women are not required to wear Tefilin, this issue is not as simple as it initially appears. The Gemara in Masechet Eruvin (95) cites the view of two Tanna'im Rabbi Meir and Rabbi Yehuda that women are, in fact, included under the obligation of Tefilin. What more, the Gemara records a tradition that Michal, the daughter of King Shaul, wore Tefilin and that the Rabbis of her time did not object to this practice.
However, Tosafot on that Gemara brings a different version of this account from the Pesikta, which tells that the Rabbis of the time indeed objected to Michal's practice of wearing Tefilin. Accordingly, the Shulchan Aruch rules that women are exempt from the obligation of Tefilin, and the Rama, based on Tosafot, write that women who wish to be stringent and wear Tefilin should be admonished to refrain from doing so.
It should be noted that the Targum Yonatan Ben Uziel (an ancient Midrashic, Aramaic translation of the Torah) in Parashat Ki-Tetze translates the verse, "A man's garment shall not be worn by a woman" (Devarim 22:5) as referring to Tefilin and Tzitzit. Therefore, women should be discouraged from wearing Tzitzit or Tefilin.
Why, then, did Michal wear Tefilin, and why did this practice - according to one version meet with the Rabbis' approval?
The Kabbalists explain that Michal knew that internally she had the "soul of a Zachar." On some Kabbalistic level, her essence was that of a Zachar, and on this basis the Kabbalists explain why she never bore children. Accordingly, her situation was unique and allowed for her wearing Tefilin. Other women, however, should not don Tzitzit or Tefilin.
Summary: Women are exempt from the Mitzvot of Tzitzit and Tefilin, and even if they wish to wear Tzitzit and Tefilin they should be instructed not to do so.
