Since you said there is treatment to improve or fix the condition causing the pain, why has he not taken that path?
Lortab is a drug that loses it efficacy with continued use. While difficult to bear, it is ultimately better for him to undergo a cessation period of using lortab. It allows your body to reset so a lower (and safer) dosage is as effective as the (likely) higher and higher dosage he required to reach the same level of benefit. In addition, while the efficacy of the drug is reduced with continued use, the lethality remains the same. That is one reason addicts die from the drug; they must continue to take higher and higher dosages to reach their high but the amount required to kill them does not increase. I'm not saying your husband is taking it for non-medical use. Simply explaining that the cessation is not a bad thing for him. The pain does not cause additional injury (as you suggested). It is simply pain.
Your husbands abuse of OTC analgesics will not allow for a legal suit if he experiences organ damage. The harmful side effects are well documented and included on every container and as such, a successful suit for abusing the medication is simply not going to happen.
As you mentioned sending patients to pain clinics for long term treatment of pain is SOP with his current doctor. In today's world it is that way with many doctors. Pain treatment is a specialty so why do you have issue with his doctor sending him to a specialist for treatment? Pain clinics keep a closer watch on the use of meds to treat pain than a PCP generally can. They also can recommend alternate therapies, both medicinal and non-medicinal, that a PCP may not be up to date on. Treating pain is their specialty. While is may seem harsh and cruel to refuse pain meds, you don't seem to realize that is sometimes the best path of treatment.
I have some close associates that have dealt with severe pain for many years. One was weaned from hydro without his knowledge. Although he claimed of severe pain if the hydro was knowingly reduced, upon using a placebo he responded to that just as well for the reduction of pain as actually using hydro. As the dosage of hydro was continually reduced to absolutely none at all, while on the placebo there was no claim of pain like when knowingly removed from hydro. In other words; they had a psychological dependency on the medication. Not saying your husband is in the same boat but it is difficult to determine simply by asking the patient if they are experiencing pain. The mind is a very complicated organ.
The other guy I know has had myriad surgeries to treat his issues. He had an implantable tens unit. He claimed no relief from it and has discontinued its use. He eats pain pills yet he still has severe pain issues. I honestly don't know if he is simply dependent on the meds or his pain is such it does not respond well to the meds. In either case I question his continued use of the specific meds he is currently using. They are not providing the relief he seeks so why is he still using them?
While it is a horrible reality to face, sometimes there just is no treatment for a persons pain. Some pain will never be abated such the patient can live a reasonably pain free life....
And that is why your husband needs to stay with the pain clinic and their directives so he can get the most beneficial treatment for his pain. Lamenting on how this may be malpractice makes you sound more like an enabler to a drug addict than a concerned wife wanting the best treatment for her husband. Whining that lortab is the only treatment that provides benefits is not the attitude of a wife that wants her husbands pain to be managed as best as possible but simply wants to aid him in obtaining hydrocodone, whether you realize what you are doing or not.