Take the issue of executive privilege. Democratic congressional leaders investigating the mass firing of US attorneys in 2006 have long demanded that former political aide Karl Rove and other Bush officials testify before Congress. But they've refused to appear, citing executive privilege – the legal doctrine that holds a president is entitled to keep conversations with staff private, in order to promote candor.
On July 30, a federal judge rejected the White House's claim that executive aides have immunity from congressional oversight. But the legal wrangling on this issue is likely to stretch on well past election day. It remains to be seen whether the next Congress will care to pursue this issue once Bush himself is out of office.
On executive privilege "Congress has not been that successful," says Mr. Thurber.
What oversight can achieve
The purpose of congressional oversight is not necessarily legal change, however. This counterpart of Congress's legislative powers is also meant to reveal problems and ensure the exercise of constitutional responsibility on the part of the executive branch.
Rep. Henry Waxman (D) of California, chairman of the House Committee on Oversight and Government Reform, has long championed congressional oversight authority as an often overlooked, vital function.
Done right, it can shape national policy just by producing public information, said Mr. Waxman at a 2006 symposium on the subject.
In 1994, Congress held extensive hearings into the practices of the tobacco industry. These did not lead to any enacted bill – then, or in subsequent years.