Can someone over stay in USA for 12 hours?

The difficulty with overstaying 12 hours in the US is that such may cause a difficulty with your mother's coming back to the US in the future. An overstay technically invalidates the underlying visa, and so your mother might have to obtain a new visa prior to coming into the States. If she is allowed to come into the country without a visa under a visa waiver program, she may encounter extended questioning at the airport when she arrives from an immigration inspector.Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.