You take the department's three strongest programmers and have them browse through the candidate's github (or equivalent code sharing site) for an hour and then

You take the department's three strongest programmers and have them browse through the candidate's github (or equivalent code sharing site) for an hour and then grade them on a scale from 1 to 5. Candidates without github get zero points. Hire the candidates with the highest average score. It's that easy. The problem for most companies is that they don't know who their strongest programmers are.