Effective 28 Aug 1943
509.480. Reduction of assigned claims to the extent of all counterclaims. — Except as otherwise provided by law as to negotiable instruments, every assigned claim shall be subject to be reduced to the extent of all counterclaims which the obligor had against the plaintiff's assignor at the time of notice of the assignment.
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(L. 1943 p. 353 § 80)