A plaintiff is entitled to recover prejudgment interest -- i.e., interest accruing through the date judgment is entered -- if plaintiff can prove the exact amount claimed to be due by defendant, and the dates during which plaintiff was deprived of use of that sum.
In Oregon state court there is an additional procedural hurdle to recovering prejudgment interest: plaintiff must both request interest in the prayer of the complaint, and plead facts sufficient to show an entitlement to prejudgment interest. Today in Tasaki v. Moriarty, the Oregon Court of Appeals reiterated that longstanding pleading rule, and held that plaintiff met the pleading standard even though the prayer in the complaint didn't mention prejudgment interest, but simply prayed for $25,000 "together with any interest accumulated on such sum."
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