Collection calls and letters

I am writing this for my brother. Late 2005, he became disabled and a paraplegic. Since then, he hasn't had a job of any kind. His sole income is his disability. Since that time, he has not paid any creditors nor has he obtained any new credit other than the basics of phone service, cable, and electricity. What he gets from his disability goes to wards basic living expenses and his medical needs. There is little to none left over each month to even pay any decent amount to creditors.

I am in the process of helping him with collection calls and letters he began receiving a couple months ago. I sent one validation letter to Portfolio Recovery Associates for a Capital One credit card he hasn't paid since 2005. I am planning to send the same to the other collection agencies that have sent him letters or have called.

I know the SOL for Texas is four years. I have also pulled my brother's credit reports and the latest that any account was placed for collections is September 2006. That is well past the SOL.

So am I correct in assuming that these collection agencies have no right based on law to collect these debts or file a lawsuit? That I would need to send each collection agency a C&D letter pointing out the fact that these are beyond the SOLs?

Also, I read somewhere but cannot remember where or find it now that even if a person was sued and had a judgment against them that they would not have to pay due to their sole income being from disability. I am not sure about this but was wondering if there was any truth to it.