[Code of Federal Regulations] [Title 21, Volume 9] [Revised as of April 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR1311.50] [Page 144-145] TITLE 21-FOOD AND DRUGS CHAPTER II--DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE PART 1311_Digital Certificates--Table of Contents Subpart B_Obtaining and Using Digital Certificates for Electronic Orders Sec. 1311.50 Requirements for recipients of digitally signed orders. (a) The recipient of a digitally signed order must do the following before filling the order: [[Page 145]] (1) Verify the integrity of the signature and the order by having the system validate the order. (2) Verify that the certificate holder's CSOS digital certificate has not expired by checking the expiration date against the date the order was signed. (3) Check the validity of the certificate holder's certificate by checking the Certificate Revocation List. (4) Check the certificate extension data to determine whether the sender has the authority to order the controlled substance. (b) A recipient may cache Certificate Revocation Lists for use until they expire.