Complex sentence: Stevens kept track of the impact of the Ahrens ruling as it was relied upon in Eisentrager and even later wrote a biography of Rutledge for a law review where he used Ahrens as an example of Rutledge's skill and care as a justice.
Split into simpler sentences: Stevens kept track of the effect of the Ahrens ruling as it was relied upon in Eisentrager. In his later biography of Rutledge for a law review, he used "Ahrens" as an example of Rutledge's skill and care as a justice.