“Relating to or causing much discussion, disagreement, or argument.“ So defines MerriamWebster the term controversy. „Abortion is a highly controversial subject.“ Or „a decision that remains controversial.“ Or „He is a controversial author.“
First know use is 1583. Synonyms: argumentative, contentious, disputatious, hot-button, polemical. Antonyms: noncontroversial, safe, uncontroversial.
Bit which topics are safe, which unsafe, in the American context? Which will not lead to an argument, which will? How can a person not native to the U.S. know the answers to these questions?