Here’s a passage from Exodus 23.  See if it makes sense to you:

You shall not spread a false report. You shall not join hands with a wicked man to be a malicious witness. You shall not fall in with the many to do evil, nor shall you bear witness in a lawsuit, siding with the many, so as to pervert justice, nor shall you be partial to a poor man in his lawsuit. You shall not pervert the justice due to your poor in his lawsuit. Keep far from a false charge, and do not kill the innocent and righteous, for I will not acquit the wicked. And you shall take no bribe, for a bribe blinds the clear-sighted and subverts the cause of those who are in the right. You shall not oppress a sojourner. You know the heart of a sojourner, for you were sojourners in the land of Egypt.

Make sense?  Stays on topic.  It is obviously a paragraph about justice.  The final sentence may seem to drift but it makes sense to say to liberated slaves that the point is to not enslave others.

OK.  But that’s not actually the passage in Exodus.  Here it is with the material I extracted put in bold.

You shall not spread a false report. You shall not join hands with a wicked man to be a malicious witness. You shall not fall in with the many to do evil, nor shall you bear witness in a lawsuit, siding with the many, so as to pervert justice, nor shall you be partial to a poor man in his lawsuit. If you meet your enemy’s ox or his donkey going astray, you shall bring it back to him. If you see the donkey of one who hates you lying down under its burden, you shall refrain from leaving him with it; you shall rescue it with him. You shall not pervert the justice due to your poor in his lawsuit. Keep far from a false charge, and do not kill the innocent and righteous, for I will not acquit the wicked. And you shall take no bribe, for a bribe blinds the clear-sighted and subverts the cause of those who are in the right. You shall not oppress a sojourner. You know the heart of a sojourner, for you were sojourners in the land of Egypt.

One way to take this is the point that, if it is wrong not to help someone out who hates you or whom you despise, how much more to actively participate in mob violence/kangaroo court proceedings against him or anyone else.  However, I think there is a related point.  Most of us aren’t actively seduced into unjust prosecution (not true right now in the PCA but usually).  We all imagine ourselves moral heroes.  But if we don’t automatically help out people who need help, even if (we presume to judge that) they don’t deserve it, we’re not the moral heroes we pretend we are and we will not be able to resist the mob pressure when it comes.