Probability For Thee, Mere Possibility for Me
And that's exactly as things ought to be. When I got to Beaumont, TX, one of the first and most notorious of all judicial hell holes, I was appalled by what this lawyer/biochemist saw. Plaintiffs' experts were willing to testify to anything (for a fat fee) and were being allowed to do so as long as they promised to say that e.g. it was more probable than not that the plaintiff's pancreatic cancer was caused by formaldehyde from plywood in his trailer. Meanwhile, a defense expert, willing only to say that plaintiff had multiple risk factors for pancreatic cancer (like smoking) far more potent than formaldehyde and that plywood was at best a negligible factor, was not allowed to testify about any possible alternative causes at all since she refused to swear that any single possibly causative factor more likely than not actually caused plaintiff's cancer. The result was that plaintiff's experts, almost all of the Collegium Ramazzini-variety who passed the red-face test only because they believed that essentially every cancer was the result of exposure to man-made toxicants, could testify to anything, while more measured and critical-thinking experts could not testify at all.
"Causation must be pr oven on a more likely than not basis" said one judge over and over, and no argument to the effect that plaintiff bore the burden, and not the defendant, would change his mind. The result, I'm sorry to admit, was that we were forced to find experts as willing to sing whatever song paid for their supper as those employed by plaintiffs. Whatever the result it bore little relationship, if any, to our quest for truth.
The good news is that courts are starting to get it - that there are credentialed nitwits and judicial polymaths - and that the latter can see through the logical fallacies of the former though they haven't an alphabet soup of letters beyond J.D. Take Benkendorf v. Advanced Cardiac Specialists Charted, for example.
"Requiring defense experts to testify based only on reasonable medical probabilities would effectively prevent defendants in many cases from presenting testimony regarding causation unless their experts could declare that a particular alternate cause more probably than not was the cause of plaintiff's injury." The "inequities would abound" were a court to rule otherwise. "[W]e agree with the majority of jurisdictions that have addressed the issue and hold that an expert witness called by the defense to testify about causation ... may testify about 'possible' causes of the plaintiff's injury. A defendant ... need not prove another cause for plaintiff's injury, but may ... testify as to alternative causes tending to undercut the plaintiff's contention that the defendant's alleged negligence more probably than not caused the injury."
Benkendorf is a med/mal case but nails the burden of proof of causation. Tomorrow (assuming we get our response out to SCOTUS on something else) a Bayesian smackdown on why false positives grotesquely outnumber the false negatives in toxic tort / mass tort litigation.
