WASHINGTON — The Supreme Court agreed on Friday to let an Obama administration lawyer take part in the argument on March 26 on the constitutionality of California’s Proposition 8 ban on same-sex marriage in that state.

As of now, the March 26 morning argument in Hollingsworth v. Perry is scheduled for one hour. It might well be allowed to run beyond that if, as expected, the Justices get actively involved in questioning the lawyers.

U.S. Solicitor General Donald B. Verrilli, Jr., last month asked the Court to allot the federal government ten minutes of time to present its views as an amicus in that case; the government has not previously taken any part in that case.

Verrilli told the Court that lawyers for the two same-sex couples who challenged Proposition 8 had agreed to give up to the government ten minutes of their usual allotment of thirty minutes.

The argument in Hollingsworth will actually cover not only the question of the constitutionality of Proposition 8, but also the question — added by the Court when it agreed to hear the case — on whether the sponsors of that ballot measure had a legal right under the Constitution’s Article III (that is, “standing”) to pursue their appeal.

The Ninth Circuit Court had struck down the measure, and the sponsors then asked the Supreme Court to review the case.

It is unclear whether the government lawyer who appears will argue about the “standing” issue, since the legal brief Verrilli filed in that case does not even mention it. However, the Justices will obviously have the option of asking for the federal government’s views on that issue, too.