Can I have my wife shave her legs, and can I shave or trim hair of my legs and back. Is it permissible in Islam?

All perfect praise be to Allaah, The Lord of the Worlds.  I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

There are three rulings as far as the person's hair is concerned.

First:  The hair which should not be removed completely or partially, such as the beard for a man, and the eyebrows for both men and women. The Sharee'ah forbids shaving this hair or removing some of it.

Second: The hair which should be removed, such as the hair of the armpits, pubic hair, and the moustache (for the man). The Sharee'ah orders Muslims to remove this hair. 

Third: The hair which was not mentioned by the Lawmaker, there is no ruling concerning this hair. The Prophet Muhammad, sallallaahu ‘alayhi wa sallam, said: “And what the Lawmaker didn't mention is a favor (can be done or left).” [Al-Bazaar and At-Tabaraani] The person thus has the choice between leaving, removing (partially or completely) such hair that grows on the nose, the forehead, the arms, the legs and the hair that grows abnormally. There is no Islamic ruling concerning it.

Allaah Knows best.