The head of a family values group testified Tuesday that marriage is in such a weakened state in the U.S. that extending the institution to same-sex couples could be its death blow.

David Blankenhorn, president of the Institute for American Values, a private think tank, took the witness stand for the defense in the trial challenging California’s ban on same-sex marriage.

“My best judgment, if we move toward a widespread adoption of same-sex marriage, I believe the effect will be to significantly further and in some respects culminate the process of deinstitutionalization of marriage,” Blankenhorn said.

Read the rest of Lisa Leff’s AP article here.