halacha - Shaking hands with the opposite gender?

What's the story: Can a man shake hands with a woman (or vice versa) in a business setting?

Answer

There's a prohibition against touching any member of the opposite gender other than your spouse or close relatives. Many opinions say that's only "affectionate" touching, "such as hugging and kissing." Others say no, it includes all touching. (Rabbi Yehuda Herzl Henkin, in Hakira Journal, discusses these opinions and their sources; he strongly believes that the former is the majority opinion.) So we have three questions:

A.) Is the prohibition all touching, or only "affectionate" touching?
B.) What is the Halachic definition of "affectionate"? (See above article for more on this)
C.) How to interpret a business handshake?

Depending on how you answer A, B, and C, the modern-day opinions will literally range from "it's absolutely fine, even in a social setting" (as had been the practice among Orthodox Jews of German ancestry not that long ago) to "not even if your life is at stake!" (R' Chaim Kanievsky). There's also the distinction between you offering your hand first, and responding to someone else's outstretched hand. (If the other person isn't looking for a handshake, do you need to go there?) R' Moshe Feinstein noted that many people do it, though he wasn't crazy about the idea.* It's said that the Bostoner Rebbe would shake a woman's hand if she offered it; Rabbi Dovid Cohen of Brooklyn quotes his mentor, Rabbi Yitzchak Hutner, that a handshake isn't about affection, it's about basic human respect ("derech eretz, not derech chiba"). On the other hand (pun intended), many Orthodox Jews have long worked with the assumption that it's prohibited (which also avoids slippery-slope problems), so be prepared to meet people with that practice.

• Note: Rabbi Hershel Schachter (in his Issues in Nursing mp3) cites several students of Rabbi Feinstein who said he was more lenient on the subject when asked in person.

For those who don't shake hands, it often helps to explain that the practice is 100% gender-symmetric and is not about Judaism disparaging women. Another way to say it is "I'm sorry but as a religious policy, I don't touch any woman/man other than my spouse." (This may get the response "gee I wish my spouse had the same policy ...")