The state Board of Education approved the first-in-the-nation mandate in July after a forceful last-minute recommendation from Gov. Arnold Schwarzenegger. The move was opposed by California's school superintendent.
Superintendent Jack O'Connell and education groups questioned whether the state had the money, staff and training to handle the requirement.
Just half of California eighth-graders currently take full algebra, up from about 34 percent four years ago. But only about a quarter of those who take it score proficient or above on standardized tests. The rate is even lower for black, Hispanic and poor students.
Opponents argued the decision was made hastily and that the public did not have adequate time to comment. The California School Boards Association and the Association of California School Administrators sued in September.
In her ruling granting a temporary restraining order, Judge Shelleyanne Chang agreed the two groups would "suffer irreparable injury before the matter can be heard" formally. She ordered the state Board of Education not to make any further decisions on the algebra test until a Dec. 19 court hearing.
The Schwarzenegger-appointed board of education was scheduled to take up its plan to phase-in algebra over the next three years during a meeting next week.
Scott Plotkin, executive director of school boards association, said the restraining order validates his belief that the board overstepped its authority.
"Prior to making their decision, the (board of education) didn't provide the public with an opportunity to express how such a change in policy will have significant ramifications for all aspects of the educational system," he said.
State Board president Ted Mitchell said he had not yet seen the judge's ruling but called the delay unfortunate.
"I think the state has a great deal of planning to do to meet this objective," Mitchell said. "Californians are ready for this discussion, and I am hopeful that this current ruling does not delay the kind of deliberation that will be necessary."
Critics say pushing students into higher-level math too early could increase the dropout rate. Algebra I is a requirement to graduate from high school, but many students need remedial classes or a pre-algebra course first.
O'Connell had proposed a new eighth-grade test that would have measured some algebra standards, but not all.