David-Paul Sip
Fuck...typing as I think here. So because he contributed to the legal matrix Scott UNDERSTANDS the mechanism by which it operates VERY clearly. His understanding is what allows him to tell the TRUTH since his knowledge is a first hand experience. Others are only able to guess and pass this off as knowledge at best.
Plus there's the "only time the Admiral ever lost in court is when they cheated" which makes telling the truth easy. The legal matrix is unable to entrap and/or enslave him so because of what he knows he also has no reason to LIE.