Complex sentence: Benson found errors in punctuation, capitalization, and pluralization in the language of the Amendment as ratified by many states, which he asserted meant that those states had not properly ratified the Amendment.
Split into simpler sentences: Benson found errors in punctuation, capitalization, and pluralization in the language of the Amendment as ratified by many states. He used the errors as a basis for his contention that those states had not properly ratified the Amendment.