Legal Question in Civil Litigation in California

The party sending out the paperwork is supposed to be the one serving a copy on all other parties.

The party serving the discovery requests must serve them on all parties, not just the one(s) to whom the discovery is directed. All parties must receive copies of the responses as well, but the responding parties will be responsible for serving them.

The rules are very simple.

Rule 1: Once a defendant "appears" in the action by filing ANYTHING with the court and serving it on the plaintiff, the plaintiff is responsible for providing copies of that filing to any defendants who appeared earlier, and copies of anything filed or served by anyone earlier in the case to the newly appearing defendant. After that, every party is responsible for sending their own copies of things.

Rule 2: Any and all documents that must be "served," must be sent by the party serving the document, to every party who has appeared in the case. So the party filing a motion must serve every other party with the motion papers, not just the party against whom the motion is made, and a party issuing discovery demands must serve every other party, not just the party on whom the discovery demand is made. Then the party opposing the motion or responding to the discovery, etc., must serve their responsive papers on every other party who has appeared.