Reported / Citable
Background
After an unusually severe San Francisco rainstorm, a retaining wall separating uphill and downhill residential properties failed. Soil from the uphill parcels slid into the downhill backyards, leaving mud and debris. The uphill owners sued the downhill owners and asserted, among other theories, strict liability for loss of lateral support—the support neighboring land naturally receives from adjoining soil. The downhill owners countersued.
Before trial, the court excluded the strict-liability theory because no excavation had caused the loss of support. Judgment was entered against the uphill owners. One downhill owner, Mary Coulton, also recovered litigation costs that included about $32,960 in expert-witness fees based on a Code of Civil Procedure section 998 settlement offer made jointly to multiple uphill plaintiffs. The uphill owners challenged both rulings.
The Court’s Holding
The First District affirmed the judgment on liability. Reviewing California statutes and common-law lateral-support principles, it held that strict liability for withdrawal of a neighbor’s natural lateral support depends on excavation activity. A retaining-wall failure brought about by weather, without excavation by the adjoining owner, does not fit that doctrine. Other fault-based theories may be available depending on the evidence, but the plaintiffs could not impose liability without fault under the rule they advanced.
The court reversed the expert-fee component of the cost award. A section 998 offer can shift certain post-offer costs when the recipient fails to obtain a better result, but a joint, unapportioned offer to multiple plaintiffs is generally invalid unless those plaintiffs possess a true unity of interest. Coulton bore the burden of establishing that exception. The uphill owners had separate property interests and potentially distinct injuries, and the record did not show the required unity. Because the joint offer did not let each plaintiff independently evaluate and accept a defined share, it could not support expert-fee shifting.
Key Takeaways
- California’s strict-liability doctrine for loss of natural lateral support requires excavation; a wall collapse or soil movement alone is not enough.
- Property damage from a failed retaining wall may still support negligence, nuisance, contract, or other theories if their elements can be proved.
- A section 998 settlement offer directed jointly to several parties is risky unless it allocates amounts or the offering party can prove a genuine unity of interest.
- Shared litigation goals or family or ownership connections do not automatically make separate property claims a single indivisible interest.
- The party seeking expert-fee shifting bears the burden of showing that an exception saves an otherwise invalid joint offer.
Why It Matters
The opinion supplies a practical boundary for retaining-wall and slope-failure disputes, which are increasingly significant for California property owners facing intense storms and unstable terrain. Lawyers should investigate excavation history, wall ownership and maintenance duties, drainage, soil conditions, and causation before selecting a strict-liability theory. Where excavation is absent, the case must usually be built around proof of fault or another recognized duty.
The section 998 ruling has broader litigation consequences. A settlement offer designed to shift expert costs must be capable of clear acceptance and valuation by each recipient. When multiple owners, businesses, or family members hold separate claims, allocating the offer is usually safer than relying on a unity-of-interest exception that the offeror will later have to prove.