One paper by Celinet Duran of the State University of New York at Oswego studied political violence between 1990 and 2020. It found that there were far more frequent and deadly attacks by the hard-right than the hard-left, although left-wing violence increased throughout the study period. A separate tally by the Anti-Defamation League, an advocacy group, shows that 76% of extremist-related murders over the past decade were committed by those on the right. Such tallies, however, depend on how extremism is defined and how ideology is assigned. The ADL uses public records such as media reports and police filings to reach their numbers. But those who commit violence often leave a messy trail of resentments that defy easy classification, and some are clearly mentally ill.
