[lobotryas]

Except the “have them show off personal projects” route can be discriminatory. At least by giving people standard questions/puzzles your team (hopefully) determined as being relevant you are giving everyone the same chance at success.

[ghostpepper]

I think it's important to clarify what you mean by "discriminatory". I think many people equate that term with "criminal" and I'm not sure if that's what you meant to imply.

After all, to discriminate can also mean to accurately select the good programmers from among the bad.

The law (which varies by country) says which things you are not allowed to discriminate based on, but after that it's up to the employer, is it not?