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Several factors contributed to the demise of apartheid in the land where that term originated, South Africa. Inspired and timely leadership within South Africa was an important ingredient. But international agitation and pressure, based on a widespread sense of moral outrage, undoubtedly were also critical. The international response included unofficial boycotts and official sanctions, with great and lesser powers alike contributing.

International opposition to the most conspicuous current example of apartheid—Israeli subjugation of Palestinian Arabs—is not nearly as ubiquitous as opposition to the South African variety had become near its end in the early 1990s. But there are signs that it is growing. Organized efforts are aimed at boycotting products from...