Sideburns

The Torah commands us (Lev. 19:27): "You shall not cut off the sides of your head, nor shall you destroy the sides of your face." The first part of this commandment is a prohibition of shaving one's sideburns. Let us leave for another post what is considered cutting off the hair on the sides of one's head and assume that it refers to any kind of removal, including cutting with scissors and applying depilatory cream. The question that remains is what are the borders of the sideburns -- sides of one's head. Let us address here only the bottom border of the sideburns, that one is forbidden from removing.

The Rivan (Pseudo-Rashi to Makos 20a sv. shetayim) writes that the sideburns continue to below one's ear, i.e. that one may not remove the hairs that grow along the side of the ear (but one may shorten them). However, immediately prior to that (sv. chayav) he writes that the bottom of the sideburns is on the side of the ear. This is also the view of many other rishonim (Ritva, Nimukei Yosef, Rashi to Shevu'os 2b).

The Shulchan Arukh (Yoreh De'ah 181:9) rules strictly on this issue and considers the sideburn to end below the ear. Many acharonim follow suit and cite this view without dissent, such as the Chasam Sofer (Responsa 1:154) and the Mishnah Berurah (Bi'ur Halakhah 251 sv. afilu; cf. Nidchei Yisrael ch. 26 and Kuntres Tiferes Adam 1:3, both in vol. 2 of the Chafetz Chaim's Collected Writings).

However, there are also acharonim who follow the majority position in the rishonim, that the sideburns only continue until the side (middle) of the ear or the end of the hard part of the ear, notably the Kozhaglover Rebbe (to whom floor 5A of the YU library is dedicated) in Eretz Tzvi (3:5) and the Imrei Yosher (2:183:2).

Other topics worthy of discussion are how many hairs need to be retained on the sideburns -- all, majority or just a few; whether using scissors or an electric shaver violates this prohibition; and how wide must the sideburns be kept. For more on all this, see R. Yaakov Haber's article in Beis Yitzchak 24 (1992), p. 168ff.

The bottom line, however, is that it is very, very difficult to justify the practice of those who shave their sideburns above the middle of the ear. Not impossible, but very, very difficult. The big leniency, that only some follow, is to shave one's sideburns below the middle of the ear. But above that... ask your rabbi.