Those Black Codes were enacted before Reconstruction and were, in fact, one of the reasons the Radical Republicans used for implementing it. So if you're looking for others to blame you'll have to try again.
BTW, have you ever heard of indentured servants? Seems that was pretty popular in the North (another form of legal slavery except it was inflicted on Irish immigrants.)
Except that indentures had a limited time frame while slavery was forever. Indentured servants were not considered property. Indentured servants could not be sold, or have their childern and spouses sold. Indentured servants had rights under the Constitution. But you're right. Other than that they were exactly like slaves. </sarcasm>
Yea, you're right, those damn ungrateful Irish just didn't know how good they had it < /sarcasm>:
And we all know how well treated blacks were in most of the North post war: