It's a risky PR tactic to blame a victim who was using a company's product. Sometimes it is necessary, especially when lawsuits are pending. Tesla finds itself in this predicament: It is blaming the driver of one of its cars for a fatal accident. This has put a strain on its relationship with the accident investigator, the National Transportation Safety Board and the Board tossed Tesla from the analysis of what happened. At issue is the semi-autonomous driving mode in the vehicle. It has been behind several accidents when drivers took their attention off the road and the system failed to note another vehicle or a barrier. Tesla already has problems reaching production goals for its mid-priced sedan. It doesn't need more pressure, but it is getting it. The company and Elon Musk are teetering on the edge of failure. Any bad news like this can push them over the edge.