Don't confuse Article I and Article III judges.
Administrative law judges are employees of federal agencies doing adjudication work. (These are the Article I judges) Congress and the agencies can set up any job requirements they want for these adjudicators, since they are really just agency employees.
Article III judges are the "real" independent federal judiciary including the supreme court and are appointed by the President and confirmed by the Senate. The only qualification for them is that they be appointed and confirmed.
http://en.wikipedia.org/wiki/Article..._III_tribunals