This is an interesting question about a sensitive topic.  Some people lose mental acuity as they age.  Also, people get sick and that can affect how well they perform their jobs.  Many federal judges have a great deal of experience, which is good, but the aging process and other factors can take their toll.  So what happens?

1. It is well-known that there are informal efforts by federal judges to encourage a fellow judge to retire if the judge is losing his or her mental capacities.  I don’t know about this in detail – – it happens behind closed doors.  But I think we all have had personal experiences where, for example, we need to have a conversation with someone who is losing his ability to drive safely or to perform his job as well as he used to – – I assume the conversations among federal judges are similar.

2. Federal law provides judges with an option to resign because of a physical or mental disability.    

The law also details a procedure for the President to appoint a new federal judge if a judge who is eligible to resign because of a physical or mental incapacity fails to do so.  The procedure requires that a majority of judges in a Circuit’s judicial council first issue a  “certificate of disability.”  I’m not aware of any recent examples.

3. Another federal law allows older judges to enter into “Senior Status” where they take on a reduced work load.  Many judges choose this option.