SACRAMENTO, Calif. >> A measure that would divide California into three parts won’t appear on the ballot in November, the state Supreme Court decided today.

The justices ordered the secretary of state not to put the ballot initiative before voters, saying significant questions have been raised about its validity. The court will now consider the merits of a challenge brought by an environmental group.

The Planning and Conservation League argues that dividing the nation’s most populous state into three would drastically change California’s government structure beyond what can be accomplished through a ballot initiative.

Venture capitalist Tim Draper, who has spent more than $1.7 million supporting the initiative, has said it would be inappropriate for the court to block it from going before voters.

Neither side immediately responded to requests for comment on the court’s ruling.

The initiative, which could appear on a future ballot if the court ultimately rules in its favor, seeks to divide the state into Northern California, California and Southern California. Its supporters argue the state has become ungovernable because of its size, wealth disparities and geographic diversity.

Northern California would comprise the Bay Area, Silicon Valley, Sacramento and counties north of the state capital. California would be a strip of land along the coast stretching from Los Angeles to Monterey. Southern California would include Fresno and the surrounding farming communities, reaching all the way to San Diego and the Mexican border.