What Proclaimed Jews to be second-class citizens?

Prior to the American Revolution, Jews were second-class citizens in just about every country on the planet. Different states in the US ended second-class status at different times, but legal discrimination against Jews in the US only ended with the Civil Rights act of 1964. In Europe, Napolean ended legal discrimination against the Jews of his empire -- this is remembered as the Emancipation of the Jews. During the counter-revolutions that followed the fall of the Napoleanic Empire, Jewish rights were attacked, but most of these attacks were short lived. In Russia, Jews remained second class citizens until the Russian Revolution, and then under Stalin, their rights were attacked (to a greater extent than the rights of other Russians). England ended second-class citizenship for Jews gradually, with the biggest step in 1867.

But my guess is that you're asking about Germany. Jews were emancipated in most German lands when Napolean conquered those lands, and this emancipation lasted (with brief reversions) until Hitler ascended to power. Then, things went downhill. The Nurnberg Laws put Jews solidly back into second-class status in 1935, although there were earlier restrictions.