Association president Robert Travas told Hina on Tuesday the Fiscalisation Act was in contravention of the Constitution's definition of the legal profession as an independent service to provide legal aid.
He said the legal profession was not an economic activity but an independent service of the judiciary, and that this position was upheld by the Constitutional and Supreme Courts in other cases.
Travas said the International Association of Lawyers, which represents bar associations in 110 countries, and the European Union's umbrella organisation of bar associations knew of no case in which fiscal cash registers would apply to lawyers.
Those two organisations have written to the Croatian government but received no reply regarding a meeting proposal and their arguments, said Travas.
Only Bosnia and Herzegovina and Serbia attempted to introduce fiscal cash registers for lawyers but their governments scrapped the idea after meeting with representatives of those two organisations.
Croatia's law on fiscalisation in cash transactions went into force on January 1.