Raise Dead: The Cleric simply points his finger, utters the incantation, and the dead person is raised. This spell works with men, elves, and dwarves only. For each level the Cleric has progressed beyond the 8th, the time limit for resurrection extends another four days. Thus, an 8th level Cleric can raise a body dead up to four days, a 9th level Cleric can raise a body dead up to eight days, and so on. Naturally, if the character's Constitution was weak, the spell will not bring him back to life. In any event raised characters must spend two game weeks time recuperating from the ordeal.This description is characteristically ambiguous and demands interpretation. The way I read the timing rules, a seventh level cleric can only raise those freshly slain (one turn? one day?), since the example given has an 8th level cleric able to raise those that have been dead for four days, and that deadline increases by four days every further level gained.
The most obvious need for a ruling relates to constitution. What defines a "weak" constitution? Does this refer to the "withstand adversity" or survival chances given on page 11 of Men & Magic? (You can see the chances in my OD&D ability scores post.) That seems like a reasonable interpretation. I think a constitution check would be a more elegant resolution system, but I want to stay close to the original rules where possible.
The "two game weeks" recuperation fits nicely into how I have been handing time passage already. I assume that one week passes between sessions, representing downtime and recovery, unless there is some urgent reason compelling continuous adventuring (this happened once that I can remember, when the PCs were in pursuit of a sorcerer). So a raised PC would be unable to participate in the following session (the player could temporarily run a retainer). In game terms, this seems like a small XP progression speed bump (if a PC dies and is raised, they miss out on one session worth of XP).
The spell description says nothing about side effects, and of course there should be some. What marks are left on a character's body or mind from a layover in the land of the dead? Are there cosmic consequences to calling someone back from eternal rest? Perhaps the land of the dead is forever drawn closer to the land of the living at the site of a raising. Perhaps there is a chance that something else comes back along with the soul of raised character. I have some half-baked thoughts on raise dead consequences here.
Here is a preliminary ruling. A raised character must make a survival check (using the percentage as determined by constitution score). Failure means the character is not raised, and can never be raised. If the check is successful, the character is restored to life but also loses a point of constitution permanently. Further, life and death are not to be trifled with, and there will almost certainly be some other consequence to tampering with the order of things.