The proposition, which specifically defines marriage as the legal union between one man and one woman was passed by California voters in the 2008 general election.
The LDS Church played a part in getting the measure passed, encouraging church members to donate time and money to the Prop 8. campaign.
Since its passage, the church has been sharply criticized for its role in Prop. 8's passage, while some church property has been vandalized.
Tuesday's ruling called the proposition unconstitutional.
In response to Tuesday's ruling, church spokesmen Scott Trotter issued the following statement:
“The Church of Jesus Christ of Latter-day Saints regrets today’s decision. California voters have twice determined in a general election that marriage should be recognized as only between a man and a woman. We have always had that view. Courts should not alter that definition, especially when the people of California have spoken so clearly on the subject.
“Millions of voters in California sent a message that traditional marriage is crucial to society. They expressed their desire, through the democratic process, to keep traditional marriage as the bedrock of society, as it has been for generations.
“We recognize that this decision represents a continuation of what has been a vigorous public debate over the rights of the people to define and protect the fundamental institution of marriage. There is no doubt that today’s ruling will intensify the debate in this country. We urge people on all sides of this issue to act in a spirit of mutual respect and civility toward those with a different opinion.”
----Information from: The Church of Jesus Christ of Latter-day Saints.