Whether you need a lawyer to write a demand letter in a personal injury case depends on the type of case that you have, and the size of the case (what's at stake, in other words).
The general rule is that you do not need a lawyer to write a personal injury demand letter in a small and easy case. But, if your case is more complicated or involves larger damages, you probably need a lawyer. An insurance company is not going to take an unrepresented person seriously if that person is asking for a lot of money. Nor will an insurer pay a lot of attention to someone who is making a demand in a case where liability is not at all obvious. Basically, the only types of cases that an unrepresented person can credibly negotiate with the insurer are small car accident and slip and fall cases, and also some workers compensation settlements.
More likely than not, if you do not have a lawyer, you are going to have difficulty getting an insurer to pay you more than about $20,000 to $25,000 to settle a personal injury case, unless you are willing to take very short money to settle the case. If, for example, you are willing to accept $50,000 to settle a $200,000 car accident case, most insurers would probably agree to that. But insurers will rarely pay that much money to an unrepresented person to settle a case if the unrepresented person is looking for top dollar.
Rear end collision cases are pretty straightforward, but liability in slip and fall cases, particularly staircase injuries, is often difficult to prove. An easy staircase liability case is someone who is walking down a staircase when the stairs collapse. But let's say that you slip on the stairs, and you aren't sure why you slipped. Proving liability in most staircase accidents generally requires an expert witness to measure all aspects of the stairs and review the building codes. If you fell on a staircase that was not obviously defective and do not have a lawyer, you will have very little chance of convincing an insurer to make a reasonable settlement offer.
Insurers are often willing to make settlement offers to unrepresented employees in workers' compensation cases. In fact, they prefer dealing with people without lawyers in worker's compensation cases. But, be careful. Although the insurers will be glad to discuss settlement with you, it is very unlikely that they will be willing to pay anywhere close to top dollar to an unrepresented person. If you have a workers' compensation case, do not have a lawyer, and are thinking about trying to settle the case, you should read this article on settling a workers compensation case. You should also contact a knowledgeable workers' compensation lawyer so that you can be informed of your legal options in your particular situation.
If you decide to try to settle your own case, what should your demand letter look like? It should be short, not more than two or two and a half pages, clear and concise, polite, and address the liability (responsibility for your injuries) and damages (your losses) in your case in an objective, non-argumentative way. See this sample letter to find out what it might look like.
You should spend not more than a paragraph or two explaining the liability. If liability is very straightforward, you can address liability in about two sentences. If, for example, the defendant ran a red light and crashed into you, you would say something like, "This case involves a collision at Main and Market Sts. Liability in this case is very straightforward. Your insured was driving northbound on Main St. and negligently ran the red light, crashing into my vehicle." If liability is more complicated, then of course it will take you longer to explain it. But you should always be able to explain why the defendant is negligent in two paragraphs or less.
With respect to damages, you need to provide the following information:
You should be able to provide all of this information in about a page and a half. Along with your demand letter, you should also send documentary proof of your lost earnings (copies of some recent paystubs and/or a letter from your employer) and copies of all of your medical records and bills relating to your treatment from the injury. It is also a good idea to make a spreadsheet of your medical treatment and bills. That way, the adjuster will have a one page summary of all of your treatment and its cost.
You'll also make the actual demand, which is a dollar amount you'd be willing to accept in order to settle the case. For more on how much to demand, see How Much Should You Ask for in the Demand Letter?
Then, send it all off to the adjuster and plan to follow up with the adjuster by phone in about 3 to 4 weeks if the adjuster hasn't contacted you first.
As always, if you run into problems dealing with an insurance company, you should contact a knowledgeable personal injury lawyer.