"After an existence of nearly 20 years of almost innocuous desuetude, these laws are brought forth"

This quote by Grover Cleveland is referring to laws that had remained in presence for nearly 20 years, however had actually been largely overlooked and forgotten. The laws had actually been in a state of "harmless desuetude," suggesting that they had actually been non-active and not imposed. Cleveland is suggesting that these laws are now being restored into the general public consciousness and are being implemented again. This might be due to a modification in public opinion or a shift in the political landscape. It might also be due to a new leader or federal government taking power and wishing to make their mark by imposing laws that had actually been forgotten. Whatever the factor, Cleveland is recommending that these laws are now being imposed again after an extended period of lack of exercise.