Federalism complicated the guarantee of personal rights because Federalism created two types of government, state, and federal government and for a long time there was confusion which one should respect personal rights.
The 14th Amendment was one of the Reconstruction Amendments and granted citizenship rights and equal protection to former slaves. This Amendment was the center of various discussions because for a long time there was a belief that only the federal government should respect it not the states governments.
Over time the Supreme Court of the US has ruled that both federal and state government have to guarantee personal rights in a process called incorporation.