49 C.F.R. § 40.203
What problems cause a drug test to be cancelled unless they are corrected?
(a) As the MRO, when a laboratory discovers a “correctable flaw” during its processing of incoming specimens (see § 40.83), the laboratory will attempt to correct it. If the laboratory is unsuccessful in this attempt, it will report to you that the specimen has been “Rejected for Testing” (with the reason stated).
(b) The following is a “correctable flaw” that laboratories must attempt to correct: The collector's signature is omitted on the certification statement on the CCF.
(c) As the MRO, when you discover a “correctable flaw” during your review of the CCF, you must cancel the test unless the flaw is corrected.
(d) The following are correctable flaws that you must attempt to correct:
(1) The employee's signature is omitted from the certification statement, unless the employee's failure or refusal to sign is noted on the “Remarks” line of the CCF.
(2) The certifying scientist's signature is omitted on Copy 1 of the CCF for a positive, adulterated, substituted, or invalid test result.
(3) The collector uses a non-Federal form or an expired CCF for the test. This flaw may be corrected through the procedure set forth in § 40.205(b)(2), provided that the collection testing process has been conducted in accordance with the procedures in this part in an HHS-certified laboratory.