Can I apply for disability insurance without a lawyer?

Yes, you can apply on your own. When you do, however, be certain that your application is supported by strong medical evidence, preferably coming from a medical specialist if possible. If the insurer denies your claim, talk to an experienced lawyer. Getting help from someone experienced is essential. This will allow you to better understand the reason for the denial and, if the lawyer takes your case, the plan will be to examine the shortfalls in your application with a view to building a stronger case.