Fun fact: by the early 1800s in the US, some pro-slavery politicians sought the end of the Transatlantic Slave Trade for fear of exactly this. This sometimes brought politicians who were against the Trade because of, like… ethics? into temporary, uneasy alliance with staunchly pro-slavery ones. The US banned it domestically by 1808, but the SCOTUS still heard cases about its legality under international law.
International Norms and Politics in the Marshall Court's Slave Trade Cases - Harvard Law Review

Ten years ago, an essay in The American Historical Review suggested that renewed attention to the Founding’s international context presaged a “paradigm shift in...

Harvard Law Review