In the case Rzecznik Praw Obywatelskich (C-390/15) the Polish Constitutional Court had expressed some doubts regarding the validity of the difference in taxation between digital and printed publications.

It asked the CJEU whether that difference was compatible with the principle of equal treatment and whether the European Parliament was sufficiently involved in the legislative procedure. The Court found that the exclusion of digital books, newspapers and periodicals from the application of a reduced rate of VAT where they are supplied electronically is not contrary to the principle of equal treatment.