There are laws that can be enforced to remove slums

<title>Get rid of trash by enforcing the laws
660.04 Filthy accumulations
660.05 Sidewalk repair
1860.03 Authorized receptacles for trash
1860.04 Disposal of solid waste
Property Maintenance Code (PMC) Sec. 302.1 Exterior Property Areas, Sanitation
PMC Sec. 304.1 Exterior Structures, General
PMC Sec. 304.2 Exterior Structures, Protective Treatment (e.g. paint)
PMC etc etc etc through everything about a house or building that could possibly go wrong, inside and out.

You don’t have to be a lawyer - you don’t even need to be half-bright - to look at the slumlord properties in Newark and perceive their lawless status.

The mayor is considering abandoning the above ordinances by handing over control for Newark’s cleanliness to the County Health Department. The Property Maintenance Code would, in that case, be considered a failed experiment after only three years and property owners would again be subject to ham-handed enforcement tactics by health inspectors along with harassment from complaints by anonymous busybodies.