Last month the Spanish Constitutional Court overturned provisions in Spanish electoral law that were introduced in December 2018 mirroring the UK's exemption for political parties gathering data on voters' political opinions in the Data Protection Act 2018 (see my blog: https://insights.doughtystreet.co.uk/post/102et20/political-views-data-protection-and-exemptions-for-political-parties).
The case was brought by the Spanish "Defensor del Pueblo" (ombudsman) on the basis that the provisions were unconstitutional because they violated various rights including the rights to protection of personal data, freedom of opinion and political participation. He highlighted the risk of big data being used to alter and manipulate political opinion as revealed by the Cambridge Analytica scandal and the need for detailed and effective legal provisions to limit the scope of political parties' use of personal data to protect society from that risk.
In the UK, the political parties exemption was passed by Parliament with virtually no debate despite the wider concerns raised by the Information Commissioner's Office in their report "Democracy Disrupted? Personal information and Political Influence" published last July and the contemporaneous publicity about Cambridge Analytica. The ability of political parties to access and use our personal data for the purposes of influencing our political opinions and interfering with our fundamental rights should be a matter of serious concern. Political parties benefit from the law as the ICO report demonstrates, so criticism of the provisions is unlikely to be driven from Parliament. The Spanish Constitutional Court ruling does, however, raise serious questions about the compatibility of UK provisions with international human rights law.