It has long been known that resurrection of the dead was possible, if the death was relatively recent (no more than 28 days ago, or the time it takes for Uluth to revolve around Rothea - although certain rituals which trap the soul within the body even after death can extend this period) - but for most of recorded history, this feat has been the providence of the greatest of priests who only performed the ritual for the greatest followers of their faith and under the most unusual circumstances. Some practitioners of arcane magic were also known to have learned this process, but they were usually vilified as necromancers and those they raised were seen as somehow "wrong", without souls, and something akin to undead monsters.
However, in modern, less superstitious times the rituals for resurrection have become more widely known and evolved into a basically secular example of ritual magic. To be sure, it is one of the more difficult rituals to master, and price of the ritual components required is usually unaffordable or ruinous for the average resident or citizen - but certainly within the means of a patrician family, and demand for such services are high enough that it is usually not very difficult to find someone with the necessary skill within the major city-states This has had profound cultural and social implications, as few rich people will stay permanently dead until they die of old age (for senescence of the human body is a problem that has not been solved yet, despite the best efforts of the Athanatos Club and other interested and highly motivated groups). From a legal point of view, most cities do not consider someone legally dead until a month has passed, and if someone has killed someone and is able to pay for a resurrection, a murder or manslaughter charge may be reduced to aggravated assault, depending on the judges.
Another side effect is that assassinations have become rather more complex, as simply killing someone important will work only as a delaying tactic or to intimidate the victim (which sometimes is the intention). To truly kill someone permanently, it is necessary to either hide the body for a month (and ward it against scrying) or to destroy it utterly - or worse, destroy the victim's soul utterly (which is extremely difficult to do, but not completely unheard of). One of the more effective tactic is to arrange things so that the victim is not missed before a month has passed, such as impersonating him or pretending that the victim is going on a lengthy journey (possibly complete with fake correspondence to pretend that the victim is still alive).
Finally, the relatively high availability of resurrection rituals have given rise to such curious services as Life Insurance, where the owner of the insurance deposits a large sum with the insurer to make sure that he is raised from the dead should he be killed - and that someone is hired to find and retrieve the body, if necessary.
Adventure Ideas
Designer's Notes & Resources
All incarnations of D&D, and many other fantasy games, have rituals that make it possible to raise the dead so that player characters who die through a few bad dice rolls can continue to be played. However, few of the settings really think through all the implications of such magics, and I wanted to do this differently for Urbis.