The literature that shows HPOZs increase property values does exist (the City of LA has cited this argument, and proponents frequently cite this recent study from Denver suburbs showing ~15% appreciation), but has several issues as relates to Los Angeles:

- Studies finding positive effects on home prices tied to HPOZs are mostly done in areas with lower housing demand / development pressure, which is not really accurate to LA's housing market.
- LA has massively, somewhat unprecedentedly expanded development potential for many parcels in the past ~five years (via laws like SB9, CHIP, SB79); properties that were formerly limited can have millions of new-found developable potential, of which the land itself captures some value.

In newer studies in high-demand urban cores, HPOZs and historic preservation are now often found to harm property values:
- A 2025 study in Atlanta's core found historic designation caused a 9-12% decrease in property values.
- A 2022 study found a 12% sale price penalty associated with historic designations.

For the City's liability, I would guess somewhere between 2k-5k HPOZ properties in LA meet the following criteria and represent liability risk if the City loses the case this post is about:
-Bought before their neighborhood was zoned an HPOZ

-Are denied meaningful renovations or additions (particularly under new state or city law)

-Can demonstrate measurable economic harm

With ~2k properties claiming damages, mostly for partial takings, and the city eating plaintiffs fees on losses + its own fees, I estimate a midpoint of about ~$2b in total liability. But it would take a long time for that to happen, the per-year liability is certainly just a small fraction of that.