Commentary for Deuteronomy 24:17

לא תטה משפט גר יתום THOU SHALT NOT PERVERT THE JUDGMENT OF THE STRANGER, OR OF THE FATHERLESS — and with regard to the well-to-do one has already been forbidden to do so (Deuteronomy 16:19): “Thou shalt not pervert judgment”, (which is a general prohibition including both poor and rich), but it (Scripture) repeats it regarding the poor in order to make one who perverts the judgment of the poor transgress two negative commands. Because it is easier to pervert the judgment of the defenseless poor than that of the rich, therefore Scripture lays down a prohibition regarding him a second time (Sifrei Devarim 281:1).

לא תטה משפט גר ויתום, during strife; be particularly on guard not to be unfair to orphans or proselytes who may be reluctant to speak up on their own behalf so as not to “make waves.” You should go out of your way to argue on their behalf so as to compensate for their feelings of insecurity in facing adversaries. [the verse is directed at the judges. Ed.]

לא תטה משפט גר יתום, "You must not pervert the judgment of a proselyte or an orphan, etc." You might be inclined to favour the proselyte in judgment seeing the Torah has commanded us so many times to love the proselyte. The Torah therefore saw fit to warn us not to pervert his judgment even in his favour. The Torah continues by writing: "do not take the garment of a widow as a pledge," in order to demonstrate that this is the only exception when the Torah does treat a widow differently in judgment compared to ordinary people. You must not take this pledge after the loan has been extended though you may take the garment as collateral at the time the loan is extended.