A group of lawyers added their voices yesterday to complaints earlier this week from various advocacy organizations about the nomination of John G. Roberts Jr. to serve on the Supreme Court, alleging in a joint letter that Roberts lacks appreciation for "the important role that an independent judiciary plays in safeguarding individual rights and enforcing legal protections."

The letter, addressed to the Senate Judiciary Committee and signed by 160 law school professors, was distributed by the Alliance for Justice, the umbrella organization for liberal advocacy groups that formally declared its opposition to Roberts's nomination on Tuesday.

The signers included 16 professors from four law schools in the capital region and one professor from Harvard Law School, Roberts's alma mater. They criticized the nominee's work in the Reagan administration as well as his decisions since 2003 from the federal appellate bench, arguing that he has sought to expand the powers of the president and law enforcement authorities while weakening protections for individual rights.

Roberts's confirmation hearing is set to start Tuesday, and a list of planned witnesses -- disclosed yesterday by the panel's Republican members -- suggests that the criticism was anticipated. On the list are three conservative law professors and two political appointees to the U.S. Commission on Civil Rights.

The senatorial presenters for Roberts will be John W. Warner (R-Va.) and those elected from Indiana, Roberts's home state, Evan Bayh (D) and Richard G. Lugar (R). Republicans are planning for six separate panels of supporting testimony, with three slots on those panels listed in the announcement yesterday as "not yet confirmed."