When it comes to civil claims, the court works on the balance of probabilities rather than the criminal standard of proof. A judge does not need scientific certainty in order to reach a conclusion, and the court must decide what is more likely than not based on the evidence available. 

One of the most difficult positions an expert witness can find themselves in is this: you have completed your analysis, agreed a common approach with the opposing experts, and the results are not what your instructing party hoped for.