Thomas Fields thought he left the war behind when he returned  from Vietnam.

But over the last couple of decades, the 63-year-old Douglasville veteran said he is still "fighting." He suffers from Post Traumatic Stress Disorder and a heart condition he says was caused by exposure to Agent Orange, and he's fighting the agency set up to help veterans like himself.

Since 1988, Fields, a former U.S. Army radio operator has tried to get the U.S. Department of Veterans Affairs to approve disability benefits for a back injury he suffered after being hit with shrapnel.

He's among the tens of thousands of veterans who find themselves involved in such bureaucratic wrangling. "I've been turned down so many times," said Fields. The last time,  his claim was sent back to the local veteran's office for reconsideration.

He receives disability payments for PTSD and his heart conditions, but says he should also receive disability benefits for his back.

A spokeswoman for the VA said the agency does not comment on specific cases without the veteran's permission.

According to the Disabled American Veterans, there  is a backlog of claims for disability compensation. As of  Nov. 7, there were 863,628  pending claims in the system, said Dave Autry, a spokesman for the DAV. Of those, more than 529,000 have been in the system more than 125 days.

But Fields is getting help through a special program at the Atlanta office of the Finnegan Law Firm.  This is the third year that the firm has provided pro bono work handling claims by veterans that have reached the appellate level.

"Most of these guys have been working for quite a while trying to get benefits," said Lori-Ann Johnson, a partner with the firm. "It's kind of frustrating for them in many cases."

The veterans program started in 2008 and has since represented hundreds of veterans nationwide.

Johnson  said the firm sees many cases involving PSTD, muscular and skeletal injuries and, increasingly, more cases of traumatic brain injury. She said the aim is to get the federal appeals court to reverse the VA's appellate board's decision or to remand the case back to the VA's regional office for further evaluation. "Either is considered a win for the veteran," she said.

Disability compensation is paid to a veteran because of injuries or disease that happened while that person was on active duty, or were made worse by that service, according to the VA website. There are multiple steps in the process once a claim is made.

A VA representative reviews the file and makes a decision on the claim.  If benefits are granted, payments begin soon thereafter. If not, the veteran may appeal. A review starts at the VA regional office but could continue to the board of veterans appeals or to the federal judicial system.

That's where Finnegan comes in. Finnegan donates all of the its awards of attorney fees paid by the U.S. government to veterans' charities.

In 2011, the firm gave more than $500,000 to national groups including the DAV. This time, the Atlanta office donated $25,000 to the Shepherd Center's SHARE Military  Initiative, which was founded in 2008 and provides care for soldiers who suffer from PTSD and who have sustained mild traumatic brain injuries while in Iraq and Afghanistan.

So far this year, Finnegan has logged more than 7,000 hours in its veterans' practice nationally.