Four months ago the architect Daniel Libeskind declared publicly that architects should think long and hard before working in China, adding, "I won't work for totalitarian regimes." His remarks raised hackles in his profession, with some architects accusing him of hypocrisy because his own firm had recently broken ground on a project in Hong Kong. Since then, however, Mr. Libeskind's speech, delivered at a real estate and planning event in Belfast, Northern Ireland, has reanimated a decades-old debate among architects over the ethics of working in countries with repressive leaders or shaky records on human rights.