Louisiana uses "mandates" many times rather than power of attorneys. A mandate is a contract of sorts. The mandate is a contract which confers the ability to handle particular affairs on someone. For example, we use "provisional custody by mandate" on this site a lot. That's basically a contract for one personal to have provisional custody; BOTH parties have to sign. However, mandates work real oddly -- though the law doesn't require a particular form, if a mandate is done to allow someone to handle a task for you, then the mandate has to meet whatever legal requirement as to form that the document has. In other words.....if you do a mandate to allow someone to do a real estate transaction for you, and the real estate transaction itself would require a notary and two witnesses, then the mandate does too. Make sense?
In Louisiana, "power of attorney" specifically relates to military powers of attorney. IN GENERAL when you see 'power of attorney' that's what it means in LA: a power of attorney done by or for a military member.
Mandates, on the other hand, can be canceled by either party (because they are a contract). Contracts end upon the death of the individual. However, they do not end upon the primary person's "incapacity", and the reason is this: in Louisiana, people are considered competent (and therefore able to carry out contracts) unless an interdiction has been done. There technically IS no incapacity without that interdiction. Okay, so there are 4 ways to end a mandate: by withdrawal of one of the parties, death of one of the parties, interdiction of the mandatary, or qualification of a curator after interdiction. the last 3 are listed in CC 3024.
So is it "durable"? not really, if you look at it from the perspective of the contract that the mandate really is.......
Oh, and one more qualification on the answer: there are some cases, specified by statute, in which a mandate cannot BE withdrawn, for example in the case of a mandate in conjunction with a mortgage that hasn't been paid off (RS 9:5388).
Louisiana did not sign the Uniform Power of Attorney Act. They do have a 'will to live' form, regarding end of life decisions, authorized by Louisiana Life Sustaining Procedures Act, La. Rev. Stat. §§ 40:1299.58.1 to –10 (I wasn't sure what part of law you were asking about, with the power of attorney question).