The UDHR was an aspirational document. It laid out what U.N. member nations agreed was a universal set of human rights, but it didn't really have any teeth. The International Covenant on Economic, Social and Cultural Rights and the International Covenant on Civil and Political Rights, adopted in 1966, were more like treaties that obligated nations to monitor their progress on the rights spelled out in the covenants and to submit regular reports to the United Nations so that it could see who was being naughty and who was being nice.

Not every nation that signed the UDHR ratified the covenants, the U.S. being one of them. The U.S. did ratify the ICCPR but not the ICESC because it took issue with the question of whether these rights could actually be put into treaties, or if they were just admirable goals that everyone should strive to achieve. Plus, some of the rights stated in the ICESC could be interpreted as requiring the rights to universal health care and food assistance, which not every politician could get behind. The U.S. has claimed that the covenants aren't "self-executing," that is, they're not valid unless Congress makes them into law.

The U.S., like many countries, has expressed formal reservations about the covenants based on the fact that certain points might conflict with or override domestic laws or constitutional principles. Still, no one disputes that the principles laid out in the covenants are pretty good ideas. But it's easier to talk the talk than walk the walk.