Glossary

Efficient proximate cause

A legal test that decides coverage by asking which cause set the others in motion and dominated the loss when covered and excluded causes combine.

Also called: EPC, predominant cause rule, dominant cause rule

Efficient proximate cause (EPC) is a legal doctrine for losses with more than one cause. Rather than counting every contributing cause, it asks which one was the predominant, or "efficient," cause: the one that set the others in motion. If that cause is covered, the loss is covered even though an excluded cause played a part. If the dominant cause is excluded, the loss generally is not.

Say a wildfire strips a hillside and weeks later heavy rain sends a mudslide into the house (hypothetical). Landslide is excluded, but a court applying EPC would ask whether the covered fire was the dominant cause. The answer depends on the facts and the state.

California is the best-known EPC state. Its Insurance Code section 530 makes an insurer liable for a loss whose proximate cause is a covered peril, and courts there have held that insurers cannot override the rule with anti-concurrent causation clause wording. Other states, Texas among them, enforce those clauses as written, so identical facts can produce different results.

Because EPC fights are fact heavy, the evidence matters: dated photos, weather records and an engineer's cause-of-loss report. See engineering reports and causation disputes and wind vs water: the hurricane claim dispute. For a denied claim, an attorney or your state insurance department can tell you which rule your state follows.

Last reviewed October 10, 2026

In the index now

Related terms

Concurrent causation The question of how to decide coverage when a covered cause and an excluded cause combine to produce one loss, such as wind and storm surge in a hurricane. Anti-concurrent causation clause Exclusion wording that denies a loss whenever an excluded cause contributes, even if a covered cause also played a part or came first. Exclusion A policy provision that removes coverage for a stated cause, type of loss, property or circumstance that the coverage would otherwise reach. Peril A specific cause of loss, such as fire, wind, theft or water, that a policy covers or excludes; it is the cause of the damage rather than the damage itself. Storm surge The abnormal rise of seawater that a hurricane or strong storm pushes onshore above the normal tide, treated as flood and excluded from homeowners policies.

Related guides

Anti-concurrent causation clauses explained One policy sentence can bar a whole loss if an excluded cause like flood played any part. How it works, which states limit it, and how to document a claim. The earth movement exclusion explained What the HO-3 earth movement exclusion removes, what it leaves covered, how it differs from settling and flood exclusions, and how to challenge a denial. Homeowners claim denied: what to do next A denial letter starts a dispute, not ends one. How to read it, match the stated reason to evidence, and use the deadlines and appeal routes you still have. Landslides and mudflow: what's covered Homeowners policies exclude landslide and mudflow, and flood insurance covers only true mudflow. How post-wildfire slides differ, and what to do. Sudden vs gradual water damage: where insurers draw the line Why a burst pipe is usually covered and a months-long drip often is not, what the 14-day seepage clause says, and how timing evidence decides slow-leak claims.

Related states

Alaska Alaska home insurance: a small, concentrated market led by State Farm, USAA and Allstate, earthquake gaps, no FAIR plan, and strong notice and claim rules.