Customary versus technological advancement tests

In an environment where the optimal level of care is unknown, we ask, under a state-of-the-art defense, which method is better able to induce parties to undertake optimal care. Assuming courts can see a noisy signal of research activities undertaken by a defendant and by some of its competitors, we ask whether courts should use a biased or an unbiased average to compare care. We find that the latter is advantageous.