Software licence agreements often contain express provisions to prohibit decompilation
The Court of Justice of the European Union has issued its ruling in the case of Top System SA v Belgian State (Case C-13/20). It considered the exceptions to the restricted acts under Article 5(1) of the Software Directive (91/250/EEC) and ruled that a buyer of a computer program was entitled to decompile it to correct errors.
Although the 1991 Directive has been replaced by the current Software Directive (Directive 2009/24/EC), the relevant provisions are substantively identical:
In this case, Top System developed software and licensed it to Selor, the staff selection agency of the Belgian government. A dispute arose between the parties about errors in the software. Selor decided to decompile the software to correct the errors without involving Top System. Top System started proceedings against Selor, claiming damages for the decompilation of its computer program without its authorisation. The Belgian courts referred the following questions to the CJEU:
The court’s ruling
The court said that decompilation falls under “reproduction or adaptation” as set out in Articles 4(a) and (b) of the 1991 Software Directive. It further ruled that the lawful purchaser of a computer program is entitled to decompile all or part of that program to correct errors affecting its operation, including where the correction consists in disabling a function that is affecting the proper operation of the application of which that program forms a part.
Although the court said that the conditions in Article 6 did not have to be satisfied, they did say that a purchaser is entitled to carry out such a decompilation only to the extent necessary to effect that correction and in compliance, where appropriate, with any conditions set out in the contract with the holder of the copyright in that program.