As one commenter already said: the best way of avoiding blaim is to not make any major modifications or write difficult code. This way you avoid creating bugs. So there is a huge risk that this will reduce productivity.

A root cause analysis should ask "five whys" as to why this happened. Tight schedules, bad specs, improper training? Blaiming everything on the individual who checked the code in is not going to be very accurate, and probably very bad for morale.