WASHINGTON — President-elect Obama will enter office with an immediate opportunity to begin shaping the federal courts by filling four dozen openings on trial and appeals courts.

Federal judges, with lifetime appointments, can be a president's most enduring legacy. President Bush receives uniformly high marks from Republicans, even those who criticized him on other issues, for his selection of Chief Justice John Roberts and Justice Samuel Alito to the U.S. Supreme Court.

Public attention typically is focused on the Supreme Court, where five justices are older than 70. Speculation about a possible opening centers on 88-year-old Justice John Paul Stevens, but any retirement is unlikely before the summer, if then.

By contrast, 14 seats are open on appeals courts or will be by the end of January. Democratic appointees are a majority on only one of the 13 federal appeals courts, the San Francisco-based 9th U.S. Circuit Court of Appeals.

These are the courts that as a practical matter have the final say on everyday issues that affect millions of people because the Supreme Court accepts less than 2 percent of the cases appealed to the justices.

"Most of the action is in the lower courts, from labor and employment law to civil rights to punitive damages to affirmative action and how the death penalty is administered," said Ilya Shapiro, senior fellow in constitutional studies at the libertarian Cato Institute in Washington.

The traditionally conservative 4th U.S. Circuit Court of Appeals, based in Richmond, Va., is the first court on which Obama can change the balance of power quickly. It has four openings and is divided now between five judges appointed by Republican presidents and five named by Democrat Bill Clinton.

Covering Maryland, the Carolinas and Virginia, the 4th Circuit hears a large share of national security and intelligence cases because Virginia is the home of the Pentagon and the Central Intelligence Agency.

Shapiro estimates that within four years, Obama can name enough judges to give Democrats majorities on nine of the 13 appeals courts.

Nan Aron, president of the liberal Alliance for Justice, has complained that Bush appointees have been more likely to rule in favor of executive authority, businesses in their disputes with workers and consumers, and limiting access to the courts.

Judges appointed by Obama can be expected to side more often with "workers, consumers, homeowners, women and people of color who were discriminated against," Aron said.