Dawn Johnsen, who teaches constitutional law at Indiana University, was an acting assistant attorney general in charge of the Office of Legal Counsel. She made her comments after former White House Counsel Harriet Miers refused to testify before Congress Thursday and Sara Taylor, the former White House political director, gave limited testimony on the firing of U.S. attorneys.

"But the problem ultimately lies with President Bush, not with Taylor and Miers," Johnsen said. "It is the president who owes a constitutional duty to accommodate Congress' legitimate need for executive branch information while protecting his own legitimate confidentiality needs. Given the inadequacy thus far in what he has offered Congress, President Bush has not satisfied that constitutional obligation."

Following Miers' failure to appear before a House Judiciary subcommittee Thursday, the committee voted along party lines to reject the argument that a claim of executive privilege exempted Miers from testifying.

Subcommittee chair Rep. Linda Sanchez, D-Calif., said the subcommittee and the full Judiciary committee will consider how to respond to Miers' refusal to comply with the subpoena.