If you are a health care professional who works with injured motor vehicle accident victims under Ontario’s statutory accident benefits system, you will no doubt have experienced an insurer’s denial of funding for a proposed treatment plan. Often, the insurer’s reason is that the proposed treatment is not “reasonable and necessary,” which is the governing legal test for eligibility for medical and rehabilitation benefits. Unfortunately, the phrase “reasonable and necessary” is not defined anywhere in the legislation. It is, perhaps, not susceptible to a straightforward definition. This is because a determination of what constitutes “reasonable and necessary” treatment not only varies from case to case but also among different clinical professional disciplines. It is also because the words themselves are ambiguous. Determining what “reasonable” treatment is can be difficult. Does it simply mean any treatment that would logically or normally be given for a particular type ...