Phillips said he began receiving threatening phone calls shortly after the couple left the store. One death threat was so severe, his sister and niece at the store had to hide in the back room until police arrived.
Attorneys for Alliance Defending Freedom argued that the First Amendment protects Phillips' right to freedom of expression as an artist.
"[J]ust as the [Human Rights] Commission cannot compel Phillips's art, neither may the government suppress it," the legal group said, adding that the conflict between Phillips' freedom as an artist and the wishes of his customers should be solved by the citizens themselves, and not by the government.
The ruling is expected to have far-reaching results, particularly in determining the extent of religious liberty protections following the Supreme Court's 2013 decision to redefine marriage to include same-sex couples. Florists, photographers and other wedding vendors have also faced lawsuits alleging discrimination for declining same-sex ceremonies.
"There is far more at stake in this case than simply whether Jack Phillips must bake a cake," the US bishops' conference and other Catholic groups had stated in an amicus brief. "It is about the freedom to live according to one's religious beliefs in daily life and, in so doing, advance the common good."
"[T]his could be one of the most important First Amendment cases in terms of free speech and the free exercise of religion in a century or more, and it could be a landmark, seismic kind of case of First Amendment jurisprudence," Rep. Mike Johnson (R-La.) said last September in a press conference at the U.S. Capitol.