why the permanency or long terms of judges is so critical to the Judiciary's effectiveness

The judiciary depends on the political branches to uphold its judgments. Legal academics often argue over Hamilton's description of the judiciary as the "least dangerous" branch. Hamilton also explains how federal judges should retain life terms as long as those judges exhibit good behavior. n England, although most agents of the Crown served "at the pleasure of the King," public officials were often granted a life tenure in their offices. [5] Lesser lords were given the authority to bestow life tenure, which created an effective multi-tiered political patronage system where everyone from paymasters to judges to parish clerks enjoyed job security. [6] Without some kind of effective control upon their conduct, this would engender intolerable injustice, as the King’s ministers would be free to 'vent their spleen' upon defenseless subjects with impunity. Check out the rest at the below link.