Who is Abraham Rosenberg from The Pelican Brief and what is their importance?

Abraham Rosenberg is a curmudgeonly, 91-year-old U.S. Supreme Court justice, Rosenberg is paralyzed after his second stroke seven years earlier but refuses to retire until there is a Democratic president, lest the Constitution be endangered. The last of the old-time liberals, Rosenberg puts government before business, individuals before government, and the environment before everything. In 34 years, he writes 1,200 opinions, amazing constitutional scholars. Refusing FBI protection, Rosenberg is shot dead in his bed, and opinion is divided over whether the killing is retribution or has a political motivation; the latter becomes clear when Justice Glenn Jensen is also assassinated.