The trial has begun of a French journalist and two former staff of accountancy firm PriceWaterhouseCoopers who are accused of leaking details of corporate tax deals that have fuelled global protests for reform.
The lawyer for the former PwC employees argues the pair are whistleblowers in need of protection.
The case, dubbed LuxLeaks, has sparked claims that Luxembourg conspired with multinational firms to deprive other EU states of tax revenue.
Civil rights groups are also up in arms over what they see as one rule for the rich and another for the poor.
Some analysts say Luxembourg authorities face a dilemma between defending confidentiality within financial institutions on whose customers the tiny state’s economy depends and avoiding damage to its public image that could discourage business.