Basically every judge lets his political ideology get in the way.
To an extent, this problem cannot be avoided. Of course, judges do let their personal opinions get in the way some times; no judge is perfect.
However, some judges do this more than others. Take, for example, William O. Douglas, who regularly made rulings on the basis of his personal views. A modern example might be John Paul Stevens. On the other hand, there are several judges who seldom let their personal views color their decisions, like Hugo Black.
Isn't a Republican who decided not to appoint a Republican as President a bad example?