Following a turnback due to a failed First Officer FMS; a B767-300 flight crew is ordered to land overweight by the airline Chief Pilot in contravention of their Aircraft Operating Manual.

Narrative

During climb; we experienced an EICAS message of 'right FMC failure'. We immediately contacted dispatch for their recommendation. Dispatch informed us that the company wanted us to return to the departure airport. At this point we were 30;000 LBS over our maximum landing weight. According to our OVERWEIGHT LANDING checklist we are to perform an overweight landing when a condition causes it to be safer to land overweight than to continue flight until at or below maximum certified landing weight. Overweight landings are at the Captain's discretion and require the use of Emergency Authority. So; we decided to hold in a dirty configuration to expedite the fuel burn down to max landing weight. ATC then notified us that dispatch wanted to contact us. We again called dispatch were told that two operations managers wanted us to land now. We responded that we were following AOM procedures for overweight landing and were going to hold until reaching maximum landing weight as we were not in an emergency situation and shouldn't compromise safety. Dispatch rogered and then ended the call. Later; we get another message from ATC that dispatch wanted to contact us. We again contacted dispatch and were told that our Chief Pilot ordered us to land overweight immediately and it was recorded. I asked dispatch to confirm that we were being ordered to land overweight by the Chief Pilot (we were still nearly 20;000 LBS overweight). Dispatch confirmed. We then informed dispatch we needed time to prepare the cabin for arrival; as they were doing a meal or beverage service. Dispatch rogered and ended the call. We informed the cabin crew and asked how much time they needed. They responded about 15 minutes. We were now ordered by the company into an unnecessary emergency situation and forced to compromise safety; by risking an overweight landing. I called for emergency equipment to be standing by and CFR was there upon landing. The overweight landing was a non-event; as the additional time the cabin needed for landing preparation burned additional fuel; and we landed only 2000 LBS overweight. However; this was an unnecessary risk to our crew and passengers. In my opinion; when we (our flight crews) have a mechanical situation; that requires an air turn back of any sort; we should not be ordered; by our company supervisors; to compromise our safety and add unnecessary risks; for the company's own benefit of avoiding additional delays and added cost. Safety should always come first and never be compromised.