Direct from the US Secret Service Website: http://www.secretservice.gov/protection.shtml
Today, the Secret Service is authorized by law (18 United States Code § 3056) to protect:
- The president, the vice president, (or other individuals next in order of succession to the Office of the President), the president-elect and vice president-elect
- The immediate families of the above individuals
- Former presidents and their spouses for their lifetimes, except when the spouse remarries. In 1997, Congressional legislation became effective limiting Secret Service protection to former presidents for a period of not more than 10 years from the date the former president leaves office
- Children of former presidents until age 16
- Visiting heads of foreign states or governments and their spouses traveling with them, other distinguished foreign visitors to the United States, and official representatives of the United States performing special missions abroad
- Major presidential and vice presidential candidates, and their spouses within 120 days of a general presidential election. As defined in statute, the term "major presidential and vice presidential candidates" means those individuals identified as such by the Secretary of Homeland Security after consultation with an advisory committee consisting of the Speaker of the House of Representatives, the minority leader of the House of Representatives, the majority and minority leaders of the Senate, and one additional member selected by the other members of the committee.
- Other individuals as designated per Executive Order of the President
- National Special Security Events, when designated as such by the Secretary of the Department of Homeland Security
I do not belive 'authorized' is the same as 'required by law', as much as 'given the authority over' more from the Secret Service:
In regard to presidential campaign, the Secret Service is authorized by law (18 United States Code § 3056) to protect:
- Major presidential and vice presidential candidates and their spouses within 120 days of a general presidential election. As defined in statute, the term "major presidential and vice presidential candidates" means those individuals identified as such by the Secretary of Homeland Security after consultation with an advisory committee.
The Secret Service provides protection for major candidates, unless declined. The Secret Service has no role in determining who is to be considered a major candidate. The Secretary of the Homeland Security determines who qualifies as a major candidate and when such protection should commence under the authority of Title 18, United States Code, Section 3056. This determination is made in consultation with an advisory committee comprised of the following individuals:
- Speaker of the House
- House Minority Whip
- Senate Majority Leader
- Senate Minority Leader
- One additional member chosen by the committee
http://www.secretservice.gov/protection_works.shtml
