As General Motors is scheduled later this year to face yet another bellwether trial over allegations it covered up a deadly ignition switch flaw, it can take some comfort from its generally-successful trial record. But critics of the bellwether system are saying that way of lining up trials does not provide an accurate way of keeping score.

Last month, the seventh bellwether trial, held before New York Southern District Judge Jesse Furman, ended in a third jury verdict in GM's favor.

Attorneys for Dennis Ward, an Arizona man who says he was injured in a 2014 fender bender caused by a faulty ignition switch in his 2009 Chevrolet HHR that made the vehicle lose power while he was driving in traffic, were unable to convince the jury that the automaker was to blame for the accident.