here and here) are based on our two controlled studies that empirically prove what was already obvious from a linguistic and logical perspective. That is, when a burden of proof instruction concludes by telling jurors "not to search for doubt" but instead "to search for the truth," the court is lowering the burden of proof below the constitutionally guaranteed reasonable-doubt standard. In both studies, mock jurors who were so instructed convicted the defendant at significantly higher rates than jurors who were simply and properly instructed on reasonable doubt.
In the second study and article, we also expanded our approach to include a post-verdict question. Not surprisingly, jurors who received the "don't search for doubt, search for truth" instruction were nearly twice as likely to mistakenly believe that conviction was proper even if they had a reasonable doubt about guilt. And jurors who held this mistaken belief (regardless of the jury instruction they received) convicted at a rate 2.5 times that of jurors who properly understood the burden of proof.
Other lawyers and I have been asking trial courts to simply conclude their burden of proof jury instructions as follows: "It is your duty to give the defendant the benefit of every reasonable doubt." This seems reasonable not only on its face -- the burden of proof is, after all, "beyond a reasonable doubt" -- but also in light of the empirical studies that prove the obvious. Nonetheless, prosecutors have mounted a flurry of arguments to preserve their burden-lowering, truth-based jury instructions on which they rely to win convictions.
In the third (and probably final) article in this series, I have collected, organized, and debunked twenty such prosecutorial arguments. My article, "The Battle over the Burden of Proof: A Report from the Trenches," will be published in the U. Pittsburgh L. Rev. this July or August. In the meantime, you can find a pre-publication draft of the article on SSRN. On page two you'll find a handy outline that groups the prosecutors' arguments into four categories. From there, you can locate the relevant portion of the article that debunks that particular argument.