Any ordinary person can go ahead and read the OAS Charter and see for themselves how US policy towards Cuba violates its very principles. But, its an interesting psychology on how those 13 US Representatives can't see it.
As I have mentioned before, all of the Latin American nations in 2005 signed a resolution that condemned the US embargo towards Cuba. And, looking at the OAS Charter, it is very clear why they did. According to chapter 4, article 20, "[n]o State may use or encourage the use of coercive measures of an economic or political character in order to force the sovereign will of another State and obtain from it advantages of any kind."
According to chapter 5, sections 25 and 26, peaceful settlement of disputes between OAS members shall follow "direct negotiation, good offices, mediation, investigation and conciliation, judicial settlement, arbitration, and those which the parties to the dispute may especially agree upon at any time... In the event that a dispute arises between two or more American States which, in the opinion of one of them, cannot be settled through the usual diplomatic channels, the parties shall agree on some other peaceful procedure that will enable them to reach a solution."
Sanctions are not mentioned.
In fact, the OAS Charter has an entire Chapter titled "Integral Development" with emphasizes economic cooperation and integration between member States. According to chapter 7, article 35, "[t]he Member States should refrain from practicing policies and adopting actions or measures that have serious adverse effects on the development of other Member States."
Obviously, the US embargo towards Cuba fails in these respects.
So, its funny how 13 US Representatives signed this letter to the OAS Secretary General to tell him that he is "contradicting" the OAS Charter. But, things are not so weird when we find out who signed this ridiculous letter.