Conflicting claims of experts in such recent cases as the tobacco/smoking controversy, the environmental depredations of acid rain, the health effects of long-term exposure to low-level radiation, the levels of safety of nuclear reactors, the health hazards of food additives and of habitual levels of consumption of specific foodstuffs, have all created a situation in which political, scientific and corporate groups consider it legitimate to deny the existence of any significant evidence in each case.
In the UK in 1994 a special inquiry into arms-related exports to Iran drew attention to a pattern of suppression of evidence on the part of ministers which effectively constituted an obstruction of justice and had nearly led to a miscarriage of justice.