A.T. Robertson Commentary Matthew 5:40

"And if any man would go to law with thee, and take away thy coat, let him have thy cloak also." — Matthew 5:40 (ASV)

Thy coat... thy cloke also (τον χιτωνα σου κα το ιματιον). The "coat" is really a sort of shirt or undergarment and would be demanded at law. A robber would seize first the outer garment or cloke (one coat). If one loses the undergarment at law, the outer one goes also (the more valuable one).