From Longman Dictionary of Contemporary Englishcause célèbrecause cé‧lè‧bre /ˌkəʊz seˈlebrə, ˌkɔːz- $ ˌkɒːz-, ˌkoʊz-/ noun (plural causes célèbres (same pronunciation)) [countable] SCLSITUATIONan event or legal case that a lot of people become interested in, because it is an exciting subject to discuss or argue about The case became a cause célèbre among feminists.
Examples from the Corpus
cause célèbre• Gun control has become the cause célèbre since the recent high school shootings.Origin cause célèbre (1700-1800) French “famous legal case” 