With the ouster of Martin Vizcarra, Peru has extended a spate of governmental instability that few countries can match, with every president since 1985 but one either impeached, imprisoned or sought in criminal investigations. With the head of Congress taking Vizcarra’s place amid public outrage and investor angst, the question is what has driven this record: is corruption worse here than elsewhere in Latin America, or party rivalry more vicious or is there a flaw in Peru’s constitutional arrang