The 280th prohibition is that a judge is forbidden from tilting the judgment against converts and orphans.
The source of this prohibition is G‑d's statement,1 "Do not pervert justice against the convert or orphan."
Therefore, for judging any Jew unjustly, one transgresses the prohibition, i.e. "Do not pervert justice."2 For judging a convert unjustly, one transgresses two prohibitions.
The Sifri3 says, "The verse, 'Do not pervert justice against the convert,' teaches that one who judges a convert unjustly transgresses two prohibitions. And if the person was both a convert and an orphan, one transgresses three4 prohibitions."
