> I am not a lawyer, but I believe that judging a job candidate based on their outside-of-work activities would actually be considered discrimination and illegal.

Discrimination is legal except for the few specific cases outlined in the various civil rights, equal pay, and age discrimination acts. Might as well take two minutes to research before making these types of posts.

Yep. Discrimination is the whole point of interviewing job candidates. You are trying to discriminate between the ones fit for the job and the ones not. :)

It depends on whether it's a coded way of asking if the candidate is married/has kids.

    Interviewer: Do you work on an open source project outside of work?
    Candidate: No, I'm too busy looking after my kids and Church activities
    Interviewer (thinking): Oh shit, I better have a damn good reason to give to HR if I reject this candidate...

"judging a job candidate based on their outside-of-work activities would actually be considered...illegal."

No, not in this case. This is relevant to the job. An employer can easily ask, "Do you have a software project portfolio?" or "What's your experience in python, professional or otherwise?" It's very much on-topic.

Whether you choose to spend your time at home programming or doing something else is relevant to your day job how exactly?

I'm not saying that external work and side projects can't lead to experience or knowledge that would make someone a good candidate. Someone might be qualified because of the work they've done on the side. But they can't be disqualified because of a lack of it.

The post you are responding to claimed that the practice is legal. You are claiming it is unreasonable. You're arguing past each other.

"Someone might be qualified because of the work they've done on the side. But they can't be disqualified because of a lack of it."

That's kind of a meaningless statement. In a competitive atmosphere, not having a qualification is the same as being disqualified if the other guy has the qualification, and among programmers, the other guy usually does have that qualification.

"Someone might be qualified because of the work they've done on the side. But they can't be disqualified because of a lack of it."

I agree 100%.