New York-based lawyer Burton Haimes will not take part in Sunday's Ethics Committee hearing, where Warner and Bin Hammam will face the allegations presented by Blazer, in order to avoid any suggestions of a conflict of interest or bias.
Blazer is general secretary of CONCACAF, the confederation for North and Central American and Caribbean football, while Warner is president of the body. FIFA presidential candidate Bin Hammam is the Asian Football Confederation chief.
Warner and Bin Hammam have denied any wrongdoing.
"This is a very, very tough case to bring and my sympathy goes out to Chuck Blazer because he had to fulfil his obligation," said Haimes.
"When someone brings instances of what has been alleged to his attention, it is his obligation under FIFA statutes to report it."
Haimes had no doubt Sunday's hearing would be free of any outside influence including that of FIFA president Sepp Blatter.
"I can assure you that the panel, I know them all, are outstanding jurists and thinkers and have a lot of integrity and total independence," Haimes told Reuters.
"I've been there since the beginning and I can tell you that there is absolute independence. When it is turned over to us, it is turned over to us as a judicial body and Mr Blatter leaves. Before he leaves he reminds us that we are independent.
"I have never had any indication or incidence where that hasn't been the case," he said.
The case sees Blazer and Warner, who have been involved in football politics for almost three decades, up against each other.
As well as long-standing partners in the region's football scene, they have been key allies in FIFA until this week.
Now Blazer's evidence could have serious consequences for Warner as well as Bin Hammam, who is standing against Blatter in the June 1 FIFA presidential election.
"He (Blazer) did what I think was the appropriate thing - I don't know if it is right or wrong, that's another issue obviously, but he has had a 28-year relationship with Jack," said Haimes.
"This will weigh heavily on him but he had to do the right thing and I think he did.
"I am sure it upset him greatly. I know him and he is a wonderful man but he had to do the right thing by the organisation, he is also a member of the FIFA executive committee.
"At some point you have to stand up for the integrity of the organisation and there has been too much in the press, allegations or questions, over some of the behaviour of people involved in a variety of things.
"Chuck is a good man, an effective leader, one of the brightest people I've met. He has a great business mind and he cares a lot about this. He had to do it, I understand why it was a very difficult thing for him," said Haimes.
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