An impressive ally in the FATCA fight has appeared in Georges Ugeux
The former Group Vice-President of New York Stock Exchange and present CEO of Galileo Global Advisors is a Belgian-born dual US citizen.
In his Should Lex Americana Be Universal: FATCA Turns Foreign Banks Into Tax Informants article for Columbia Law Review, Mr. Ugeux writes:

In my first course on International Private Law at the Catholic University of Louvain, we were taught that tax laws could not extend beyond the borders of the taxation authorities.

Yet, he points out:

The US applies Universal tax Law

He writes about technicalities of FATCA, but also reports from a personal perspective.

FATCA raises fundamental questions of privacy, but also raises questions about how it can be properly executed. Why, as a Belgian-born, dual-citizen, grandfather, am I no longer allowed to use or send money from my Belgian account for my granddaughter in Paris by using Internet banking? Why is my account subject to all kinds of FATCA restrictions while I am not required to disclose the account because its amount is below the IRS thresholds? Why can I not view the balance of my account on line?
Effectively, those accounts become useless, and it is equivalent to inciting US tax persons to close those accounts, pushing them to less regulated and transparent jurisdictions if they need capital abroad, whether it is for their business or their household…
Not surprisingly, one by one, banks refuse to open accounts for US residents or nationals. A friend of mine was refused the opening of a bank account last week in Tokyo…
This will affect Americans working outside of the United States who are not going to be able to use local banking facilities. It’s a strange version of a self imposed Yankees go home.

He suggests a delay in FATCA to ensure equity between countries.

The United States has to ask itself the question of whether its actions are legitimate and question its objectives and the ways it goes about achieving them. This is especially pertinent at a time when the United States seems to reserve a right to eavesdrop upon foreign nationals.

He asks:

Is US foreign policy using all its weaponry, including the FCPA and FATCA to impose a Lex Americana (i.e., American law regime) upon the rest of the world? Shouldn’t the US first look more closely at its own taxation system and corruption? International tax law is in urgent need of modernization with a focus on equity and fairness rather than threat and blackmail