Final answer:
Judge Eric made a mistake by being politically partisan in his decision, which undermined the nation's confidence in him as an impartial guardian of the rule of law.
Step-by-step explanation:
The mistake that Judge Eric made was being politically partisan in his decision, which led to criticism from many. Dissenting Justice Stevens commented that the judge's decision undermined the nation's confidence in him as an impartial guardian of the rule of law.