I would recommend https://clg.portalxm.com/library/keytext.cfm?keytext_id=121 as a good read on the matter.

During the Cold War, the major powers were more concerned with winning/preventing WW3, so they put human rights at the back (this is echoed in the Realist International Relations theory (http://en.wikipedia.org/wiki/Realism_(international_relations), which was dominant back then. Human Rights have no practical place in a realist point of view)

For example, the US was willing to back dictators provided they were not communist (see Indonesia for example), while the USSR was engaging in crimes against humanity at the end of WW2, which continued up until Stalin's death at least. When the Cold War ended, yes, Human Rights were back on the agenda, but besides signing some agreements that looked good (Geneva convention, Human rights declaration, etc), there wasn't a major effort to uphold them.

tl; dr- Cold War was more important than human rights.