due diligence

1 :  such diligence as a reasonable person under the same circumstances would use :  use of reasonable but not necessarily exhaustive efforts —called also reasonable diligence Editor's note: Due diligence is used most often in connection with the performance of a professional or fiduciary duty, or with regard to proceeding with a court action. Due care is used more often in connection with general tort actions.

2a :  the care that a prudent person might be expected to exercise in the examination and evaluation of risks affecting a business transaction b :  the process of investigation carried on usually by a disinterested third party (as an accounting or law firm) on behalf of a party contemplating a business transaction (as a corporate acquisition or merger, loan of finances, or especially purchase of securities) for the purpose of providing information with which to evaluate the advantages and risks involved the greatest exposure…for failure to conduct adequate due diligence arises in the context of public offerings of securities — G. M. Lawrence c :  the defense (as to a lawsuit) that due diligence was conducted