What is Reasonable Diligence?

Legal Definition
A fair, proper, and due degree of care and activity, measured with reference to the particular circumstances; such diligence, care, or attention as might be expected from a man of ordinary prudence and activity. Railroad Co v. Gist, 31 Tex. Civ. App. 662, 73 S. W. 857; Bacon v. Steamboat Co., 90 Me. 46, 37 Atl. 328; Latta v. Clifford (C. C.) 47 Fed. 620; Rice v. Brook (C. C.) 20 Fed 614
-- Black's Law Dictionary