A New Jersey judge agreed Thursday to bar an expert on business ethics from testifying on behalf of a man who blames his heart attack on the painkiller Vioxx.

Superior Court Judge Carol Higbee, who will preside over the man’s product liability case against Merck & Co. beginning next week, granted Merck’s request to keep W. Michael Hoffman from taking the stand after lawyers for the drug maker said his testimony would be subjective, would be potentially confusing for jurors and would violate court rules that limit expert testimony to scientific and technical topics.