Every now and then I submit a statement from a spouse, parent or friend in support of a disability claim. 20 CFR 404.1513(d)(4) states that Social Security will consider evidence from other non-medical sources, such as a spouse or a parent.
In an appropriate case, where you have the right person with the right story to tell, it can be powerful evidence. A non-medical, or "lay" statement is powerful evidence because it puts a disability case in a human context.
The statement is usually a 2 or 3 page typed document. It will usually tell the story of how the claimant used to be, what changed medically, and what life is like now. There is a genuineness to these statements, and they are often very moving.
The statement should be in the record when the judge reviews the claim prior to the hearing. In a typical case, prior to the hearing the judge can only review the medical records and various Social Security forms that are in the claim file. The human element is missing until the actual hearing, when the judge finally meets the claimant. The statement adds the human element to the disability claim file.
The statement often provides an excellent summary of the claim. And since the statement is in the record as evidence, you can refer in your hearing brief.
Look at the cases you have coming up for hearing. One or more of them might benefit from a statement from a spouse, parent, sibling or friend.
Update: I have written several additional posts on this topic: