The U.S. Conference of Catholic Bishops (USCCB) has filed briefs in two Supreme Court cases related to gay marriage.

In both cases, the USCCB called on justices to rule against marriage equality.

In United States v. Windsor, which challenges the constitutionality of the Defense of Marriage Act (DOMA), USCCB lawyers argued that “there is no fundamental right to marry a person of the same sex.” The brief also argues that being gay is not an orientation but merely conduct.

In contrast to the classes for which this Court has applied heightened scrutiny, what lower courts have understood to be a homosexual 'orientation' is not a trait attributable from conception or birth. Rather, particularly as framed by Respondents here, it involves a species of conduct.”

In Hollingsworth v. Perry, which challenges the constitutionality of Proposition 8, California's gay marriage ban, the USCCB urged the court to uphold the 2008 voter-approved constitutional amendment.

Given both the unique capacity for reproduction and unique value of homes with a mother and father, it is reasonable for a State to treat the union of one man and one woman as having a public value that is absent from other intimate interpersonal relationships.”

The brief added that “redefining marriage … would have widespread adverse impact on other constitutional rights, such as the freedoms of religion, conscience, speech and association.”

The Supreme Court will hear oral arguments in March and hand down a decision in June.

(Related: Bishop Salvatore Cordileone: Gay marriage is not about equality under the law.)