I do not know if there is an infallible decree re: Templars. During this golden age of the Church, there were many chroniclers and as such an extremely large amount of evidence exists about the case.
I would enjoy a debate with some one who defends them-- is that what U want? This has occured in the past and the general conlusion of this place was about 12 votes to convict and I think there was only one person who was on record as defending them-- I cannot remember who it was but I believe they are banned now.