Legal Question in Civil Litigation in California

If the other side has not answered yet then the court will not have an issue. There are some technical legalities but usually a court wants to get an accurate picture so pleadings are liberally permitted to be amended.

Actually, if the other side has not answered, amendment does not require court approval. Any number of amendments can be filed before the defendant answers. So I'm assuming there is an answer on file and leave of court to amend is required. Mr. Jefferson is right that amendments are liberally granted. Generally in order for an amendment to be denied the defendant must show inexcusable delay by the plaintiff in asking to amend AND some prejudice to the defendant if the amendment is allowed. So the earlier in the case the motion to amend is filed, the more likely it will be granted. If the prejudice to the defendant is wasted time and money on theories that have radically changed, the court can still allow the amendment conditioned on payment of some of the defendant's costs. The court can also reopen discovery or permit extra discovery when the pleadings change after substantial discovery is completed. So the prejudice needs to be pretty serious before the only remedy is to deny leave to amend. Technically leave to amend can even be granted after trial, which is called leave to amend to conform to proof. The other reason leave can be denied is if the amendment is futile or immaterial. For example an amendment to add a cause of action that does not relate back to the original causes of action in the earlier pleadings, and that is now past the statute of limitations, will be denied.