If if doesn't hinder the job, then I would assume it is not really legal, at least not ethical to discriminate color blind people.
If the job is to assemble PCB, or to repair PCB that really requires reading color codes, then I would say it makes sense to discriminate color blind people.
The same thing to age discrimination. Not hiring a 50-year old in a supermarket is not legal, at least not ethical, but not hiring a 50-year old in a SWAT team makes perfect sense.
I wasn't very clear whether I meant "right" or "legal right." Regardless of laws, do employers have a right?
Again, with the stipulation "regardless of laws," employers always have a "right" to discriminate against employees for any reason whatsoever. They don't even need a reason. It is called the "Golden Rule."
Second, non-color-blind people often have a serious misconception of that disability. It is extremely rare for a person to lack all cones and to be truly "color blind." In reality, "color blind" people see colors, but the colors and shades are different. That condition can be detected by tests that use mixtures of colors.
I have known several color blind people, including my father. Every one of them did quite well with adapting to their condition. Of course, everything in our home was painted either brown or white.
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)
More seriously, early in my career, a mentor was R/G color blind. Nevertheless, he was one of the best people I have known at reading a Gram stain, which is basically orange-red (eosin) and blue plus shape. For many years, however, laboratory accrediting agencies required testing for color blindness. Eventually, they caught on to the fact that color blind people really are not blind to color and there was no reason to continue that practice of testing as a requirement.
So, does anyone know whether a color blind person can read resistor codes? (Consider only the most common type of R/G color blindness.) Do they find it easier or harder to distinguish violet from brown than a non-color blind person? Frankly, I pull out the ohmmeter to do that, and I am not color blind.
As for legality in the USA, it is generally illegal do discriminate against an employee with any disability so long as that disability does not affect job performance after "reasonable accommodation" has been made. I suspect providing the employee with an ohmmeter is well within what would be considered reasonable accommodation.
John