The U.S. Supreme Court denied a petition fighting California egg laws.
The Missouri-led lawsuit wanted to overturn the law requirements on how to house egg-laying hens.
California voters approved the law in 2008 but Missouri, along with Iowa and four other states, challenged that.
California accounts for one in nine eggs sold in the nation.
The ruling reaffirms a November 2016, Ninth Circuit Court of Appeals decision against the challenge.