1987 - Iran Contra Affair
Little is known about the events surrounding the Iran Contra Affair are unknown (the documents were destroyed by insiders), but general concensus is members of the Reagan administration shold weapons to Iran and used the profits to fund Contra rebels in Nicaragua. The program was coordinated by Oliver North of the National Security Council and circumvented both Administration policy and the Boland Amendment which limited US assistance to rebel contras to overthrow the Nicaraguan government.
The President formed the Tower Commission (see excerpts) to look into the issue and they released their report on February 26, 1987. It criticized several members of the Reagan administration but could not determine the level of President Reagan's knowledge of the affair. It did criticize Reagan's apparent lack of knowledge regarding his staff's actions. Several Congressional hearings have looked into the Iran Contra Affair and can be found in the Government Publications Library.