"You shall not wrong an immigrant or oppress him, for you were strangers in the land of Egypt.
"You shall not afflict any widow or orphan. If you afflict him at all, and if he does cry out to Me, I will surely hear his cry; and My anger will be kindled, and I will kill you with the sword, and your wives shall become widows and your children fatherless.
"If you lend money to My people, to the poor among you, you are not to act as a creditor to him; you shall not charge him interest. If you ever take your neighbor's cloak as a pledge, you are to return it to him before the sun sets, for that is his only covering; it is his cloak for his body. What else shall he sleep in? And it shall come about that when he cries out to Me, I will hear him, for I am gracious.”
The widows and orphans are those who have no ability to bring their matter to court because they had no social or legal standing, just as a felon or the very poor do not in our society, because they cannot sue.
To do justice to the widow and orphan is, today, providing justice for those who obtain no justice in the "justice" system. For those who do not receive justice, the final appeal is to God Himself.