The standard replaces but-for causation where multiple exposures could each have caused the disease. A defendant's contribution must be substantial rather than merely present, though what qualifies as substantial is defined variably.
It originated to address indivisible injury from multiple sources.
Alternative Names:
Substantial Factor Standard, Substantial Contribution
Why it Matters?
The ambiguity in substantial is what makes this standard contested, since courts have applied it to require anything from more than de minimis exposure to a showing that the exposure meaningfully increased risk. Some jurisdictions have retreated toward requiring dose quantification, holding that substantial cannot mean any identifiable exposure. Which formulation the forum applies determines whether exposure evidence must be quantified.
Frequently Confused with
Related terms
Frequently asked questions
What does substantial mean?
Why did the standard develop?
