Anti-concurrent causation (ACC) clauses are insurance policy provisions drafted to defeat coverage whenever a loss involves any excluded peril, regardless of whether a covered peril was the predominant or even the precipitating cause. In hurricane and windstorm litigation, ACC clauses are how carriers attempt to escape liability for losses that are partly attributable to flood, storm surge, or earth movement — all commonly excluded. Understanding how Florida and Alabama treat these clauses, and what plaintiff-side pleading and proof strategies are available, is foundational to competent representation in first-party property disputes.
Standard ACC Language and Carrier Rationale
The standard Insurance Services Office (ISO) property form language reads approximately as follows:
"We do not insure for loss caused directly or indirectly by any of the following. Such loss is excluded regardless of any other cause or event contributing concurrently or in any sequence to the loss."
The excluded perils then follow — typically flood, surface water, earth movement, and governmental action. The "regardless of any other cause or event contributing concurrently or in any sequence" clause is the anti-concurrent causation provision. Its effect, if enforced as written, is to eliminate coverage whenever an excluded peril plays any causal role, even if wind (a covered peril) was the dominant or independent cause.
The carrier's rationale is underwriting clarity: ACC clauses allow insurers to price products based on discrete peril underwriting without being exposed to "seepage" claims where a nominally excluded peril loss is partially converted into a covered wind claim through causation arguments. In post-hurricane litigation, this rationale becomes a denial machine, particularly where wind and storm surge arrive nearly simultaneously and property investigators cannot cleanly separate the damage.
Florida Treatment: Sebo and the Concurrent Causation Doctrine
Florida is among the most policyholder-favorable jurisdictions in the country on ACC clause enforcement. The Florida Supreme Court's decision in Sebo v. American Home Assurance Co., 208 So. 3d 694 (Fla. 2016) is the governing authority.
The facts of Sebo are important. John Sebo purchased a home in 2005. American Home Assurance Company (AHAC) provided homeowners coverage. The home suffered major design and construction defects — a noncovered peril — which permitted water intrusion during rainstorms. Hurricane Wilma then struck and caused further damage. AHAC denied coverage for most losses, relying on the ACC clause and the exclusion for design defect. The jury found for Sebo; the trial court entered judgment; the Second District reversed, concluding that ACC language precluded coverage when multiple perils combined to cause a loss and at least one was excluded.
The Florida Supreme Court quashed the Second District's opinion. The Court held that the plain language of the all-risk policy did not preclude recovery in this case. More specifically, the Court adopted the concurrent cause doctrine for all-risk policies where independent covered and excluded perils combine to produce a loss — reasoning that under an all-risk policy, absent clear and unambiguous ACC language that specifically addresses the type of concurrent causation at issue, coverage should attach.
The Sebo holding has several important qualifications that plaintiff-side counsel must understand:
- Sebo applies most cleanly to all-risk policies. Named-peril policies may be analyzed differently.
- The Court's reasoning turned substantially on the policy's all-risk structure and the specific ACC language involved. Carriers responded post-Sebo by tightening ACC clause language in new policy forms. Practitioners must examine the exact ACC language in the policy at issue.
- Sebo did not eliminate ACC clauses or hold them per se unenforceable. It construed the specific policy against the carrier under ambiguity principles. A sufficiently precise ACC clause may still bar coverage in Florida for truly concurrent losses.
*Post-Sebo lower court application. Florida's district courts of appeal have applied Sebo to a range of hurricane loss scenarios, generally finding coverage where wind and an excluded peril combined to produce damage, absent an ACC clause drafted to unambiguously address that specific combination. Carriers have responded with policy form revisions incorporating more specific ACC language targeting wind/flood, wind/surge, and wind/mold combinations. Evaluating whether the revised forms successfully cabins Sebo* is now a routine intake question in Florida property litigation.
The efficient proximate cause doctrine. Even before Sebo, Florida courts applied the efficient proximate cause doctrine, under which the peril that set the chain of events in motion — the "efficient" cause — governs the coverage determination. Where wind strips a roof and subsequent rain intrusion damages the interior, the wind is the efficient proximate cause even if the water is the proximate physical mechanism of interior destruction. Sebo supplements this doctrine for multi-peril scenarios, but both frameworks remain in play.
Alabama: Efficient Proximate Cause as the Default
Alabama does not have a Sebo-equivalent decision. Alabama insurance law applies the efficient proximate cause doctrine as its default rule for multi-peril losses. Under that doctrine, the court looks to the peril that was the predominant, efficient cause of the loss. If that peril is covered, the loss is covered; if it is excluded, the loss is excluded — even if a covered peril contributed.
For hurricane claims in Alabama, this means: if wind was the efficient proximate cause that set in motion the chain of events leading to damage, the claim should be covered, even if flood or storm surge subsequently contributed to the loss. The plaintiff's burden is to demonstrate, through engineering or meteorological expert testimony, that wind was the efficient proximate cause rather than flood or storm surge.
ACC clauses create an additional layer of complexity in Alabama because some courts have treated them as an explicit override of the efficient proximate cause doctrine — reasoning that the clause, by its terms, eliminates the proximate cause inquiry. Whether Alabama courts will enforce ACC clauses as a complete bar to the efficient proximate cause analysis, or whether they will apply Sebo-like ambiguity reasoning, remains unsettled. The better-reasoned view, consistent with Alabama's general principle of construing ambiguous insurance provisions against the drafter, is that ACC clauses should be construed narrowly and that clear manifestation of the parties' intent to override the efficient proximate cause doctrine is required.
Pleading Strategies for the Plaintiff
In jurisdictions with favorable ACC doctrine — Florida post-Sebo being the clearest example — plaintiff-side pleading in hurricane property cases should:
1. Allege independent causation in the alternative. Even where losses appear intertwined, plead both that (a) the covered peril (wind) was the sole cause of specific elements of damage, and (b) in the alternative, that covered and excluded perils independently caused separate elements of damage, and (c) that where perils combined, the covered peril was the efficient proximate cause or the concurrent cause doctrine entitles the insured to coverage.
2. Challenge ACC clause applicability by its terms. Many ACC clauses are drafted to apply to flood, surface water, and earth movement, but may not capture every excluded peril the carrier attempts to invoke. A carrier relying on an ACC clause for "mold" damage following wind-driven water intrusion may be outside the clause's intended scope, depending on whether mold exclusion language is incorporated into the ACC provision.
3. Attack ACC clause as applied to all-risk policies. Following Sebo, a motion to dismiss or summary judgment defense based on ACC clause enforcement must be met with a Sebo argument: under an all-risk policy, the concurrent cause doctrine applies absent clear and unambiguous ACC language that specifically contemplates the combination of perils at issue.
Expert Allocation Testimony
The practical battleground in concurrent causation cases is expert testimony. Plaintiff-side preparation should include:
- Meteorological expert: establishes wind speed, direction, and duration at the specific property location, and provides a timeline of wind damage versus flood/surge inundation. Distinguishing pre-inundation wind damage from post-inundation flood damage is essential to both the efficient proximate cause and concurrent causation arguments.
- Structural engineer: provides an opinion, to a reasonable degree of professional probability, allocating specific damage elements to covered wind versus excluded flood or surge. The engineer must be prepared to testify that identified damage features are consistent with and caused by wind loading, not hydrostatic pressure or surge.
- General contractor: quantifies the cost of wind-attributable damage as a percentage of total loss, providing a basis for damages even if the carrier prevails on the exclusion for some flood-attributable items.
The allocation argument is not only a damages argument — it is a coverage argument. A plaintiff who can establish that at least some discrete elements of the loss were caused solely by covered wind, independent of any excluded peril, avoids the ACC clause entirely as to those items.
Open Questions
The post-Sebo policy form landscape has not been fully adjudicated. Carriers have drafted ACC clauses that, for example, expressly exclude losses "caused by or resulting from" flood "regardless of whether wind contributes concurrently or in any sequence." The question of whether this language unambiguously overrides Sebo's concurrent cause analysis — or whether it remains ambiguous in the context of an all-risk policy — has not been definitively resolved by a Florida District Court of Appeal since Sebo. Practitioners handling large-loss hurricane cases should monitor developments in the district courts and be prepared to litigate ACC clause enforceability de novo on each new policy form.
Conclusion
ACC clauses are the carrier's primary weapon against concurrent-peril hurricane claims. Florida's Sebo decision significantly curtailed their effectiveness for all-risk policies, but it is not a blanket invalidation. Alabama's efficient proximate cause framework offers an independent path to coverage even in the absence of a Sebo-type rule. In both jurisdictions, the plaintiff who wins the expert battle on causation allocation wins the case — which makes early investment in meteorological and engineering expert retention one of the most important decisions in the post-storm property litigation timeline.
Talk to Yates Anderson
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Informational only. Not legal advice. No attorney-client relationship is created by reading this post. Consult a licensed attorney in your jurisdiction.