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MHC Tech Law: Do dynamic IP addresses count as personal data?

Whether or not IP addresses, a type of online identifier, are classified as personal data has been the subject of considerable debate, the Mason Hayes & Curran Technology team writes.

(via In May 2016, an independent adviser to the EU’s highest court issued an Opinion finding that IP addresses are deemed to be personal data in instances where they are handled by a website operator.

The case, Patrick Breyer vs Bundesrepublik Deutschland (Case C-582/14), concerned a challenge brought by Patrick Breyer against the German state.

Breyer sought to challenge the collection, use and storage of IP access logs across state-owned websites. One of the core questions was whether IP addresses, coupled with the access time, qualify as personal data.

The court’s independent adviser – the advocate general (AG) – took the view that, in certain circumstances, dynamic IP addresses can constitute personal data.

What are IP addresses? 

IP addresses are one of the digital fingerprints left by a device accessing the internet. Website operators use and store IP addresses for various purposes, including to serve content and improve security.

These strings of numbers identify laptops, smartphones and other devices to both the internet service provider (ISP) and website operators. Usually, however, only one IP address will be assigned per subscriber, or per household. In other words, multiple devices in one household could be identified by the same IP address.

‘Dynamic’ IP addresses, as the name suggests, are dynamic rather than static, meaning that the subscriber or household is frequently assigned a ‘new’ address. As a result, the subscriber or household is not generally identified by a single, unique IP address.

Generally speaking, dynamic IP addresses are not alone sufficient to identify an individual. However, when combined with a date and time of access, the ISP can identify the subscriber.

Getting personal

Breyer brought this challenge against the German state, alleging that it was processing his personal data – in this case, his IP address logs – without a legal basis.

The German federal court referred questions to the Court of Justice of the European Union (CJEU) for determination. In particular, the German court asked the CJEU whether a dynamic IP address, held by a website operator, could constitute personal data if an ISP holds additional information that would identify the individual.

Under EU law, ‘personal data’ is information that identifies or has the ability to identify a living individual.

The AG took the view that dynamic IP addresses could be classified as personal data. However, they noted that this view should be considered in the context of the specific facts of this case. In particular, he highlighted that the German court’s question was framed in the context of a third party, the ISP, having additional identifying information.

Interpreting recitals

The AG adopted an interesting interpretation of one of the recitals to the EU Data Protection Directive.

In EU lawmaking, the recitals provide guidance on how the operative provisions of the directive should be read and interpreted. The AG focused on Recital 26, which provides that in determining whether an individual is identifiable; “account should be taken of all the means likely to be reasonably used either by the controller or by any other person to identify the said person.”

Taking a literal interpretation of this, if anyone has the ability to identify the individual, then the information should be considered to be personal data.

The AG, however, took a measured approach, forming the view that when determining if an individual is identifiable, one should consider combining data held by the party in question (in this case, the website operator) and “certain third parties”.

The AG also analysed another key component of Recital 26: the “reasonableness” of identifying the individual.

Generally speaking, it is often difficult to obtain information from ISPs to identify IP access logs. Usually, a court order – a Norwich Pharmacal order in Ireland – is needed.

However, the AG took the view that although the ISP could refuse to hand over the data to the service provider, there was still a legal possibility, albeit restrictive, that the data could be obtained.

Implication of this opinion

While these opinions are not binding, the CJEU often tends to follow them.

Here, the AG has adopted a relatively broad interpretation of Recital 26 and, therefore, of the concept of personal data.

The AG’s position is significant. He has found that dynamic IP addresses are personal data, despite the fact they are only identifiable when combined with ISP-held information. Previously, in EMI and Others vs Eircom, the Irish high court found that IP address logs in the hands of record labels were not personal data.

‘This could lead to a situation where any website that holds IP logs will be required to treat these logs as personal data’

The AG’s view could arguably be confined to the facts of this case. However, if the CJEU were to follow this opinion, it could lead to a situation where any website that holds IP logs will be required to treat these logs as ‘personal data’, as they do names and addresses, and comply with data protection obligations.

What’s next?

The court’s ruling is scheduled to be published on 19 October 2016. It will be interesting to see if, and to what extent, the court follows the AG’s opinion.

Many EU regulators already take the view that dynamic IP addresses are personal data, particularly when coupled with other identifying information. The Irish Data Protection Commissioner (DPC) has recently published guidance regarding the anonymisation and pseudonymisation of personal data. It sets down the DPC’s position on what should be considered personal data.

Lastly, it is worth highlighting that IP addresses are expressly viewed as personal data under the EU’s incoming data protection law, the General Data Protection Regulation (GDPR). With this in mind, the outcome of this case may only have a short-term impact.

It is not clear, however, the extent to which dynamic IP addresses, in the hands of someone other than the ISP, might be viewed as personal data under the GDPR. This case could, however, offer guidance on this point.

The content of this article is provided for information purposes only and does not constitute legal or other advice.

Tech Law is a weekly series brought to you by Irish law firm Mason Hayes & Curran, whose legal tech team advises the world’s top social media organisations and emerging start-ups. Contact a member of the MHC Technology team or visit for more information. Image: agsandrew/Shutterstock 6 ottobre 2016

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