Results of the 1973 Church Committee Hearings, on CIA misdeeds, and the 1984 Iran/Contra Hearings....

"In its consideration of covert action, the Committee was struck by the basic tension--if not incompatibility--of covert operations and the demands of a constitutional system. Secrecy is essential to covert operations; secrecy can, however, become a source of power, a barrier to serious policy debate within the government, and a means of circumventing the established checks and procedures of government. The Committee found that secrecy and compartmentation contributed to a temptation on the part of the Executive to resort to covert operations in order to avoid bureaucratic, congressional, and public debate."

The Church Committee

http://pw1.netcom.com/~ncoic/cia_info.htm#Introduction