Q. What is the Halacha regarding using electric shavers? Does lift and cut make any difference?
Thank you

A. There are basically three different opinions in regards to using electric shavers. Early Gedolim including Chofetz Chaim (Likutey Halochos – Makos 21a) was against even using mechanical clippers that cut the hair until nothing remains, considering this as the hashchassa or destroying facial hair that the Torah prohibits. However, scissors may be used to remove facial hair since they do not accomplish total destruction; as the hair is cut in between the top and bottom blade. Therefore, stubble equal to the thickness of the bottom blade of the scissors remains. Following this stringent position the Chazon Ish, the Steipler Gaon, and many other Poskim prohibited the use of all electric shavers.( Igros Chazon Ish 1: 197- 198, Hadras Ponim Zoken, Kovetz Teshuvos 32, Minchas Yitzchok 4: 113, et. al.)

However, many Poskim maintain that the violation of this Torah prohibition is not determined by the size of the hair that is left, but by the instrument used, and if there is direct contact of the cutting blade with the skin. Horav Moshe Feinstein, Horav Yosef Eliyahu Henkin zt”l and other Poskim permitted the use of ordinary electric shavers, since they function as scissors, utilizing two blades to cut. The inner blade of the machine, does not cut by itself, and must be assisted by the outer screen of the shaver. The screen traps a hair within it, and as the inner blade approaches it, the hair rubs along the side of the screen and they both cut the hair simultaneously. This may not apply to the “lift and cut” shaver. According to the company that manufactures them, a lift and cut shaver first lifts up the hair and then pulls it into the machine. Once the hair is inside the shaver, the inner blade cuts it by itself closely to the skin, cutting it off completely at skin level, thus achieving a very close shave. A similar problem may involve Micro-Screen Foil shavers. The Terumas Hadeshen, (quoted by the Rema, Y. D. 181: 10) maintains that when shaving with scissors, a person should be extremely careful to either hold the bottom blade still, using only the top blade to cut his hair, or to use scissors where the bottom blade is incapable of cutting by itself. The reason for this is because extra precaution should be taken to prevent mistakenly shaving solely with the bottom blade, even a minute amount, since this is equivalent to using a razor.
There is a possibility that in micro-screen foil shavers, the micro-screen foil itself has cutting edges that can cut by themselves. This screen is comparable to the bottom blade of scissors, since it touches one’s skin. Rabbi Avrohom Blumenkrantz zt”l writes the following in Hilchos Pesach; “…The new problem being discussed today is that the micro screen shields are so thin that they on their own have a cutting ability. We tested it and found out that if you bring a hair through the holes in the micro screen shield and by just moving the hair without too much pressure it could cut the hair.”
Other Poskim are even more lenient The Zomet Institute follows the recommendations of an article by Rabbi Shabtai Rapaport (Techumim 10, p.200.) He proposed the criterion for not being scissor like and prohibited, whether the blade is capable of cutting hair without rubbing against the screen that covers it. And his conclusion was, that in the machines with a metal cover screen the blade alone cannot cut the hair, therefore the cutting is done by both and permitted.
Horav Shlomo Miller’s Shlit’a is reluctant to permit outright the use of any electric shaver, reflecting the first opinion mentioned above, and he strongly recommends not to use the lift and cut or micro-screen versions. However he permits the use of trimmers that leave over a stubble that is minuscule

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a