1.How have laws been written and enforced in the U.S. over the past 400 years to disproportionately punish black Americans?

Your question is wrong America is only 244 years old and our Constitution was written only few years after Independent british And for your information there is no law are make to punish them they were being punished because of slavery slaves are know as one property that people own just like now in car or back then horse so they were just being used unfairly. In the end finally thanks to 16th of president U. S President Abraham Lincoln approved the Joint Resolution of Congress submitting the proposed amendment to the state legislatures ( Passed by Congress on January 31, 1865, and ratified on December 6, 1865, the 13th amendment abolished slavery in the United States. And it keep on going 14th amendment

No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws. 15th amendment Constitution prohibits the federal government and each state from denying a citizen the right to vote based on that citizen's "race, color, or previous condition of servitude." It was ratified on February 3, 1870, as the third and last of the Reconstruction Amendments. ...does it help your question If not sorry for my to bother you with my informations