RC Fleet Management Officer Keryakov points out that the "hopeless" clause is kind of shady and up to interpretation. We however agree to cooperation against hostile threats to security in the solar system.
Dr. Grahams would like to declare several clear possibilties for a "hopeless" effort-
A. If reinforcement cannot be expected to be made in time to influence the battle, but would only avenge the fallen.
B. If, even with timely reinforcement, the enemy would still possess a greater than trivial advantage in combat-effective tonnage.
Addendum: (I propose we define this as a case where the estimated combat-effective enemy fleet tonnage would still outmass remaining combat-effective allied fleet by 20% or more. If, say, half the meson tubes on a fleet are out, that counts as roughly half the actual tonnage being combat-effective tonnage. It's an open secret that all of our nations have intrasolar monitoring arrays excellent enough to gauge the proximate amount of damage done to any fleet. Dishonesty can be known swiftly-being coy or less than truthful would be quickly obvious.)
Addendum Two: In the event that a significant technological weaponry gap appears evident between our nations and an enemy, we will adjust this requirement to a 20% disparity of estimated hull damage per second each fleet can provide. This clause is not to be invoked slightly and is intended to cover the case of extrasolar threats.
Addendum Three In the event of a probable total system extinction scenario, I would release each nation to escort whatever refugees that may exist.
The NAU sperm cannon will be made available for reseeding purposes.C. If the defending nation itself declares an effort to be hopeless, and releases nearby nations from the duty to help.