The answer to this question depends on the type of voter and their location.
Citizens living overseas, or those deployed in the military (commonly referred to as Uniformed and Overseas Citizens Absentee Voting Act or “UOCAVA” voters) have a nationwide provision that allows them additional opportunities beyond the traditional methods of voting. Some states allow the electronic return of a marked ballot (i.e. via email or web portal), while others require the voter to print their ballot and mail it from overseas. For the states that already allow electronic or fax return, mobile voting is likely a legal and viable option. For more information on how UOCAVA applies across different states, visit https://www.fvap.gov.
Some states also allow voters with disabilities to vote using the same methods as UOCAVA voters, so in many instances, the same provisions and allowances above would also apply for that demographic. Two states allowing this include West Virginia and Utah.
For the population at large, Voatz has been working with jurisdictions on a pilot-by-pilot basis to collect data on mobile voting and its operational success in the field. These metrics and case studies can help challenge some of the broader legal hurdles and garner support for the electronic delivery and return of the voted ballot.