Chester A. Arthur played a crucial role in shaping U.S. immigration policy, particularly through the Chinese Exclusion Act of 1882. His administration took significant steps to enforce this law, which aimed to curb Chinese immigration and was the first law to restrict immigration based on nationality or race. Arthur's support for this act reflected the growing anti-Asian sentiments in the U.S. at the time. His policies marked a shift towards more restrictive immigration practices, setting a precedent for future legislation that would continue to shape U.S. immigration policy for decades.