D.C. Mun. Regs. tit. 3, § 504
504.1 An applicant for voter registration who is unable to sign or to make a mark on a voter registration application, due to a disability, may apply with the assistance of another person; provided, that the voter registration application is accompanied with a signed affidavit from the person assisting the applicant which states the following:
(a) That he or she has provided assistance to the applicant;
(b) That the applicant is unable to sign the registration form or to make a mark in the space provided for his or her signature;
(c) That he or she has read or explained the information contained in the application and the voter declaration to the applicant, if the applicant cannot read the information; and
(d) That he or she has read or explained the penalties for providing false information on the registration application, if the applicant cannot read the information.
504.2 If the applicant is unable to sign his or her name, the applicant may place his or her mark in the space provided for his or her signature and have that mark witnessed by the person assisting by having the witness also sign the voter registration application.
SOURCE: Final Rulemaking published at 43 D.C. Reg. 1078, 1081 (March 1, 1996); as amended by Final Rulemaking published at 57 D.C. Reg. 3267, 3272 (April 16, 2010).