The U.S. Supreme Court will begin hearing arguments on Monday in the ObamaCare lawsuit filed by nearly 30 states that claim the new law is unconstitutional. A group has issued a petition to attempt to force Justice Elena Kagan to recuse herself from the case.
Kagan had worked for the Obama Administration prior to being named by Barack Obama as his new Supreme Court appointee. Her role in the Administration as Solicitor General was to represent the federal government of the United States before the U.S. Supreme Court.
This means that in all legal cases involving the federal government, Kagan's role was to argue for the Obama Administration in lawsuits brought against the government.
In the ObamaCare case it is clear from the evidence that Kagan was personally invested in advocating for the passage of the new healthcare law. This was the official stance of the Administration, and thus, by extension, it was the official stance of Kagan as Solicitor General for the Administration.