Convict leasing is still not illegal federally, only in some states is it outlawed rather than just having been phased out, it amounts to near enough the same thing and in many cases was proven to be deadlier than regular slavery. If you buy a slave you are likely to at least try and keep them healthy enough to work but leased prisoners you only pay for their time so an individuals health is of no concern, many prisoners (often arrested under the black codes) were worked or beaten to death under convict leasing in the post emancipation years.