Can I apply for benefits without a lawyer?
Absolutely. You have the legal right to apply for governmental benefits and access the U.S. court system pro se (on your own, without a lawyer). In fact, you can apply for SSD benefits online.
However, every case is different and while you certainly have the right to represent yourself, proceeding pro se may not be in your best interests. An SSD attorney is especially important in making sure your SSD application is properly customized to give you the best chances of getting approved.
Though she looked at the online SSD application, Susan decided to consult with and then hire an SSD attorney. She didn't want to take a chance on making an egregious mistake and knew she'd only have to pay her attorney if she won and was awarded back benefits.