Zoning & Land Use  ·  September 27, 2026

SB 79's First Lawsuits Are About Arithmetic

Five lawsuits over SB 79 have been filed since mid-August 2026. These are usually framed as cities defying a state housing mandate. Read the petitions and a different pattern shows up: not one of them disputes that SB 79 requires upzoning near transit. Every one of them disputes a counting or line-drawing judgment the statute handed to an agency — how many trains serve a station, how many feet of sidewalk separate a parcel from it, how much of a city qualifies as an employment hub.

That is a more interesting fight, and a harder one for the challengers than the headlines suggest, because the Legislature gave at least one of those agency judgments a presumption of validity — though whom that presumption protects is itself contested.

Our explainer on SB 79 and what it changes for property owners covers the framework, the tiers and the eligibility conditions. This article is about what has actually been litigated since, and about two amendments that have landed on the statute in 2026.

What do the tier thresholds actually say?

The figures are usually reported as 72 and 48 daily trips. The numbers are real and statutory. The sentence around them is not, and the gap is the whole dispute.

SB 79 is Stats. 2025, ch. 512, which added Chapter 4.1.5 (commencing with Government Code section 65912.155). The relevant definitions in section 65912.156:

> "(r) 'Very high frequency commuter rail' means a commuter rail service with a total of at least 72 trains per day across both directions, not including temporary service changes of less than one month or unplanned disruptions, at any point in the past three years."

> "(e) 'High-frequency commuter rail' means a commuter rail service operating a total of at least 48 trains per day across both directions, not including temporary service changes of less than one month or unplanned disruptions, and not meeting the standard for very high frequency commuter rail, at any point in the past three years."

Four things the shorthand drops.

The unit is trains, not trips. The statute counts trains per day across both directions.

Whether the threshold attaches to a service or to a station is contested. The grammatical subject of both definitions is "a commuter rail service" — singular. The statute does not say a station served by 72 trains. But subdivisions (n), (o) and (p) classify stops as "served by" a qualifying service, which is how plaintiffs read the station back in. This is the question in litigation.

There is a three-year lookback. "At any point in the past three years," excluding temporary changes under a month and unplanned disruptions. A station can qualify on service levels that no longer run.

Hitting the number is not sufficient. A qualifying service makes a stop Tier 1 or Tier 2 only if the stop is also a "transit-oriented development stop" under section 65912.156(p) and sits in an "urban transit county" — defined at subdivision (q) as a county with more than 15 passenger rail stations.

One more figure worth pinning down. Tier 1 is often described as allowing up to 160 units per acre. The base Tier 1 density floor is 120 dwelling units per acre within a quarter mile of the stop, and 100 in the quarter-to-half-mile band in cities of 35,000 or more. The additional 40 comes from the adjacency intensifier at section 65912.157(e), available only to a project immediately adjacent to a stop — and "adjacent" is defined at section 65912.156(a) as within 200 feet of any pedestrian access point to such a stop.

Who is suing, and over what?

Three suits announced August 20, 2026. Californians for Homeownership and the California Housing Defense Fund, joined in San Francisco by YIMBY Law:

- City of San Diego, San Diego County Superior Court, No. 26CU043967C. The claim is that the city misused the exclusion at section 65912.160(e) for areas lacking a walking path of under one mile to a stop. The reported illustration is a parcel roughly 375 feet from a trolley station that plaintiffs say was excluded because reaching it means crossing about 100 feet of paved alley with no formal sidewalk. - City and County of San Francisco, San Francisco County Superior Court, No. CPF-26-520062. The claim is that designated "industrial employment hubs" do not meet the statutory standards for excludable employment areas, and that the city unlawfully restricted the State Density Bonus Law. Roughly 1,900 parcels are reported to be affected. - City of Montebello, Los Angeles County Superior Court, No. 26STCP02862, over what the petition describes as a complete moratorium on SB 79 developments.

Montebello is the outlier of the three. Its core theory is the Housing Crisis Act of 2019, which bars housing moratoriums, rather than SB 79's tier or exclusion provisions — so it may resolve without construing SB 79 at all.

A fourth suit, against SANDAG, was filed on or about September 10, 2026 by the same two organizations. As of September 27, 2026 we were not able to locate the court or case number in any public source, so we do not state one. The target is the San Diego Association of Governments as the metropolitan planning organization responsible for mapping transit-oriented development stops under section 65912.160(f).

The dispute is the counting question above. Oceanside Transit Center is served by four rail services. Plaintiffs count roughly 130 weekday trips there in aggregate and say the station should be Tier 1; SANDAG classified it Tier 2. Plaintiffs allege SANDAG reached that result by counting each rail service separately and finding no San Diego County service at 72. Solana Beach, which plaintiffs say SANDAG excluded from both tiers, is said to reach roughly 56 trips across two services and to qualify as Tier 2.

A fifth suit against the City of Oceanside was reported filed September 11, 2026 on the sidewalk-gap exclusion and the city's own tier count. We could not locate that petition either.

As of September 27, 2026, all five are trial-level writ proceedings and none has produced a ruling.

Does HCD's guidance settle the counting question?

This is the part most worth getting right.

HCD issued an advisory memorandum, "SB 79 Advisory Clarifications on Definitions for Metropolitan Planning Organizations," dated March 20, 2026. On aggregation it says: "In assessing whether a station meets this threshold, frequency is based on the total number of trains serving the station, including trains operated by multiple commuter rail services where applicable."

That is the plaintiffs' position, stated by the state agency. But three points cut against treating it as decisive.

It calls itself advisory. The memo states that it "is advisory and consolidates definitions discussed with MPOs, in consultation with Caltrans, which HCD has compiled at the MPOs' request to support carrying out their duties under Government Code section 65912.160, subdivision (f)." HCD therefore grounds the memo in subdivision (f) directly. An agency charged with administering a statute does not get to rewrite it in a memo, and HCD does not claim to be doing so.

It departs from the statutory text in three places. The statute says "at least 48 trains per day"; the memo counts an average per weekday. The statute says "across both directions"; the memo says across all directions — which matters at a junction station where services run on different alignments. And most importantly, the statute makes the threshold an attribute of a commuter rail service, while the memo reframes it as an attribute of the station and then aggregates services into it. The strongest textual argument available to SANDAG is that the grammatical subject of both definitions is "a commuter rail service," singular. Plaintiffs answer that the definitions operate through the stop-based framework at subdivision (p), which classifies stops as "served by" a qualifying service, and that HCD reads them that way. No court has resolved it.

The authority for the guidance is not obvious. Section 65912.160(f) requires MPO maps "in accordance with the department's guidance pursuant to subdivision (b)." Subdivision (b) directs HCD to promulgate standards on how capacity is counted in a city's inventory of land suitable for residential development under section 65583.2 — a different subject. So the aggregation question turns on a prior question: whether subdivision (f)'s cross-reference reaches a memo of definitions at all. If it does, conformity may be mandatory whatever the memo calls itself. If it does not, the memo is an agency interpretation carrying only the weight its reasoning earns. Neither reading has been tested.

Under Yamaha Corp. of America v. State Bd. of Equalization (1998) 19 Cal.4th 1, an agency interpretation adopted without rulemaking is not binding and commands only the respect its persuasive power earns. Courts determine the meaning of a statute independently.

Any statement that SANDAG violated binding state guidance is a characterization of a contested position, not a finding.

What are the plaintiffs up against?

One feature of the statute, one recent decision against these plaintiffs, and one that cuts their way.

The map carries a statutory presumption. Section 65912.160(f) gives the MPO's map "a rebuttable presumption of validity for use by project applicants and local governments." Two caveats. By its terms the presumption runs for the benefit of applicants and local governments, so whether an MPO may invoke it defensively against a petitioner is itself an open question. And a rebuttable presumption shifts a burden rather than ending the inquiry. It gets little attention, and if it applies it is the plaintiffs' central obstacle.

A statutory presumption has already been outcome-relevant for this plaintiff. In Californians for Homeownership, Inc. v. City of La Habra (4th Dist., Div. Three, No. G064286, certified for publication January 16, 2026), the same lead plaintiff lost. The court independently reviewed whether a housing element substantially complied with statute, but applied the section 65589.3 presumption of validity attaching to an HCD-certified housing element, and the section 65010(b) harmless-error rule requiring prejudice, substantial injury and a probable different result. That decision is a caution, not a precedent in the plaintiffs' favor.

But the standard of review may help them. In Ruegg & Ellsworth v. City of Berkeley (2021) 63 Cal.App.5th 277, the first published decision construing SB 35, the court declined to apply a deferential standard, observing that applications under that statute are for a "streamlined, ministerial approval process" based on "objective planning standards," and that "[t]he Legislature's choice of language makes obvious its intent to constrain local governments' discretion." SB 79 likewise sets objective criteria. That is the plaintiffs' best argument that a tier classification is not a discretionary judgment entitled to deference.

We located no published California appellate decision construing SB 79. The statute became operative as to local agencies on July 1, 2026 — earlier for an agency that adopted a compliant ordinance or alternative plan, and not until the seventh RHNA cycle in unincorporated county areas — and the oldest of these petitions was announced weeks later. Anyone telling you what courts have held about SB 79 is telling you about something that has not happened.

What changed on the statute in 2026?

Two amendments, and the one getting attention is not the one in force.

SB 722 (Wahab), Chapter 100, Statutes of 2026, is already law. It is an urgency statute effective July 16, 2026 — two weeks after SB 79 became operative as to local agencies. It amends section 65912.157 to bar SB 79 developments on sites governed by the Mobilehome Residency Law, the Recreational Vehicle Park Occupancy Law, the Mobilehome Parks Act or the Special Occupancy Parks Act. It operates without a local ordinance. From July 16, 2026 forward, SB 79 developments are barred on those sites. SB 722 does not by its terms address applications already pending when it took effect, so a project filed in the roughly two-week window before July 16 raises a separate question.

AB 2576 (Harabedian), Chapter 214, Statutes of 2026, is not yet in force. Approved by the Governor and filed with the Secretary of State on September 14, 2026, it amends section 65912.161 to broaden the historic-resource exclusion beyond local registers to include contributing sites in a historic district on the State Historic Resources Inventory and parcels individually listed on that inventory, as defined in Public Resources Code section 5020.1, keyed to designations made before January 1, 2025.

Two qualifications that matter more than the amendment itself. It is a non-urgency statute chaptered in 2026, so it operates January 1, 2027. And the exclusions in section 65912.161(b)(1) apply, "[p]rior to one year following the adoption of the seventh revision of the housing element," only where "the local government has adopted an ordinance in accordance with Section 65912.160." AB 2576 enlarges what a city may exclude, for a limited period. It excludes nothing by itself. An owner near a historic district gains nothing from it unless the city legislates.

There is also a contingency: AB 2576 contains an alternate section that operates only if AB 2415 is also enacted and AB 2576 is chaptered last. AB 2415 had not been chaptered as of September 27, 2026; the public record shows its last action as concurrence pending in the Assembly on August 19, 2026. Anyone quoting the final text of section 65912.161 should confirm which version took effect.

What is still unsettled?

Nearly all of it, and that is the honest summary.

No court has construed SB 79. No court has ruled on whether trains operated by different services at one station aggregate. No court has said whether an MPO's tier classification gets deference or independent review, or how the section 65912.160(f) presumption interacts with the objective-standards reasoning in Ruegg. The HCD advisory's authority under a cross-reference pointing at a different subject has not been tested, and neither has the underground-regulation objection that a city could raise against it under Government Code section 11340.5.

Three things are worth establishing now, with the caveat that the first is exactly what is being litigated. Check which tier the MPO map currently assigns your parcel — the map carries a rebuttable presumption of validity, not finality, and two pending petitions seek to change tier assignments at named stations. Check whether your jurisdiction has adopted an exclusion ordinance under section 65912.160, which is what makes most exclusions operative. And check whether SB 722 reaches your site, which it does without any local ordinance, and whether your city is likely to legislate under AB 2576 once it operates on January 1, 2027.

Our zoning disputes page describes how we work on these, and our article on converting retail to housing covers the parallel question of what the housing statutes do and do not preempt.

This article states the law and the litigation posture as of September 27, 2026.

Frequently asked questions

This article is general information about California law, not legal advice, and reading it does not create an attorney-client relationship. Statutes and case law change, and how they apply depends on the specific facts. Attorney advertising. Prior results do not guarantee similar outcomes. Robert B. Mobasseri, State Bar No. 193193, ROMO Law Group, Encino, California.