I ask potential hires to bring samples of their work and have them discuss it in depth.

We deal with the issues brought up by others that most developers can't really do this, by asking them to bring a piece of public code that they like and give 10 minute presentation about it.

The code that they select tells a lot and is a great starter for further discussion and finding out about how they think. It also demonstrates an essential skill, and that is evaluating other peoples work and how to work with it rather than against it.

I work in an industry that would fire then sue me for taking samples of my actual work.

Many would reply with open source or personal projects, but I will head that off by saying that not everyone does open source (for some people, 50 hours programming a week is all they want to spend) and there are many who do open source in other areas and perhaps not with the same level of professionalism and expertise.

And others of us would be in jail.

The old mantra has been: released projects.

Someone who can show their own past work, either open-source, side-project, launched projects, or work at somebody else's company ... well there is a high chance that they can at least code their way out of a wet paper bag. Probably more than that too.

Another, perhaps better, approach is to just hire a few of the most promising candidates for a couple of days. Give them a small project. See if there's a fit.

How will you verify the released projects if the person only worked in-house?

I think that the issue is not only about predicting future success but about trust as well.

Give them a small project to do, something that should take about 3-5 days.

Ugh, this is acceptable, I guess, provided the company is willing to pay an hourly wage. I'm currently in the process of looking for a new gig, and there's nothing worse than being sent a coding challenge that should take about '2 hours' (4-5, more like), and then to get a canned rejection from the recruiter stating the code didn't pass muster. This is especially annoying with companies with DEEP pockets - at least do me the courtesy of paying an hourly wage OR have an engineer on the team go over the code and give some feedback.

No candidate that you would actually want to hire would jump through this hoop. Not even ones presently unemployed.

You'd pay them. You'd take something small that needs doing, outlay a much larger than usual slice of money to it and hand it out to all of the last line of candidates.