[MRM]

In general employers are allowed to contract with employees in any way that is mutually agreeable, and the employer may discriminate on any basis that is not prohibited. These are called protected classes - race, color, sex, religion, nation of natural origin, and for people over 40 yeas old - age.

In other words, an employer can advertise that it hires only tall people and pays bonuses for everyone over 6 feet, or they hire only skinny people, or only people who listen to 60s acid rock, or whatever. But an employer cannot base pay or working conditions on the employee's races, sex, color, nation of national origon, or age after 40. You can segregate the people on the factory floor and give them work assignments based on height, but you can't give the women a certain type of job and the guys different jobs, unless the employee's sex is a bona fide qualification - like cleaning the woman's shower room. That's clearly acceptable to reserve for male employees, right? Some companies have jobs that are known informally as women's jobs, and others are open in practice only to men. Often one or the other job pays more, but there's no reason why one job or the other should be a "woman's" job. That's an equal pay issue. Essentially, there are millions of factors that go into the wages and working conditions of any given employee, but their pay and working conditions cannot be dependent on any of the protected classes - race, sex, etc.

Actually, not to put too fine of a point on it, but my height example is bad because men are taller on average than women. So unless you did a regression analysis to have the same reward for women at the same percentile in height as the men, you would be inadvertenly discriminating in favor of men through what is known as disperate impact. To avoid that but still discriminate legally based on height, you would have to match the height of the men only against other men and women against other women. So a 5'10" woman would compare to a 6'6" man, and should be paid equally.

I have long advocated for compensation systems based on height (taller being higher compensated, so to speak) but I haven't gotten anyone to go for it yet.