But that's not what how the controller is defined in the regulations. To be the controller, you must be "the natural or legal person, public authority, agency or other body which, alone or jointly with others, determines the purposes and means of the processing of personal data". If you don't even have any way to know what personal data a third party is collecting or how it's being used, and you're linking to content that is freely available but over which you have no control, you're not even close to fitting that definition.

You should have agreements in place with all your external resource providers that touch personal data.

But that fundamentally breaks most of the modern WWW, which is not a reasonable thing to do. You can't even have a personal blog linking to a jQuery CDN to expand or contract your sidebar or Google Fonts to make things look pretty at that point.

Just because you are using a third party to do the spying does not remove your responsibility.

If they're spying at your request and on your behalf, that's one thing.

But it is inherent in the technologies of the web that third parties may be doing all kinds of things without your knowledge, consent or control. Moreover, even if you have somehow satisfied yourself that there is nothing inappropriate going on when you first incorporate external content in your page by reference, there is in general no technical mechanism to guarantee that the situation will not change later. In some limited cases tools like subresource integrity can help, but they only address specific parts of the general issue.

"‘controller’ means the natural or legal person, public authority, agency or other body which, alone or jointly with others, determines the purposes and means of the processing of personal data"

If you're embedding a JS library from a CDN, then you have a lawful basis for passing the IP address of your user to a third party under Art. 6(1)(f). As long as you've performed a reasonable risk assessment about this activity and have records to prove it, you should satisfy your obligations as a controller under Chapter 4. If they go rogue and add a bunch of tracking scripts to the library, they're liable. You'd still need to notify about the breach.

If you're embedding a Javascript ad unit that does a bunch of tracking, you probably don't have a legitimate interest under Art. 6(1)(f), so you'll need consent. You're intentionally passing a bunch of personal data to a third party, so your responsibilities with regards to risk assessment are far greater. You and the ad provider probably constitute joint controllers under Art. 26.

https://gdpr-info.eu/recitals/no-15/

https://gdpr-info.eu/art-6-gdpr/

https://gdpr-info.eu/chapter-4/

https://gdpr-info.eu/art-26-gdpr/

IANAL etc.

But if you're embedding a JS library from a CDN, then as a matter of fact, you aren't passing any data about your user to the third party at all. The user's browser is doing that as part of its normal operation.

Moreover, as another matter of fact, you cannot have either any knowledge or any control over what happens next regarding any personal data the third party is collecting or how it is being processed, unless you have some separate arrangement with the third party that goes well beyond mere linking or embedding.

Logically, it doesn't seem to make much sense for you to be either the controller or the processor in that instance. However, if the third party plays either role, they may have no mechanism to communicate with your site visitor to fulfil their obligations either.

You're not absolutely and totally responsible for anything that might possibly happen under any circumstances, but you're required to implement appropriate technical and organisational measures to ensure and to be able to demonstrate that processing is performed in accordance with this Regulation (Art. 24).

If you embed a JS library from Google Cloud CDN and compile a written risk assessment with copies of Google's privacy policy for that product and their EU-US Privacy Shield and ISO 27018 certifications, you're probably fine no matter what happens.

If you embed a JS library from SuspiciousCDN.ru because someone on 4chan gave you the link and your user data ends up on WikiLeaks, you're going to have some serious explaining to do.

Do I expect visitors to my personal blog to have any security or privacy problems because I use Google Fonts to make it look nice? No.

Do I have any sort of formal agreement that is binding on Google to guarantee that, or that obliges them to notify me if they change their privacy policy in this respect? Also no.

And exactly the same applies to, for example, numerous popular JS libraries that are hosted for free on reputable CDNs.

It really all does revolve around control: as the website owner you can't control their ISP, Browser, VPNusage, etc. but you could trivially change your site from using Google Analytics to using a different system (or disable it altogether).

But the regulations don't say anything about websites. Being a controller is about whether you determine the purposes and means of processing (even if someone else is then doing that processing). Merely embedding third party content on your site doesn't even give you knowledge of that processing, never mind any control over it.

Now, if you have a formal agreement with some other service that they will process personal data for some purpose and you will embed something in your page that gives them access to that data, obviously in that situation you're acting as controller. But huge amounts of the embedding that happens in the real world don't have those formal arrangements, and if you say no-one can ever embed anything any more without formal legal agreements to protect themselves, you break a large part of the modern web both technically and culturally. I don't think that was the intent of the new regulations, nor do I think it is a reasonable thing to do.

Take it as, "I control the door to a bank vault, if I allow robbers in, I will be a complice to a crime as the crime couldn't be commited without your help". Negligence or direct intent, it can be costly. Assess your 3rd party sources very carefully, I have already removed GA and replaced them with local analytics (https://matomo.org/) as I can't trust them, they are trying to downplay GDPR and there is already a complaint written against them (https://noyb.eu not for GA though), and I have read the PDFs, they are right and quite objectively, they are guilty. I dont want to be in a same boat with them.

Yes there is a guidance, it is called GDPR, it is THE only guidance, just take the concepts, I can give you this link, it is the best I was able to find, it will help understand the GDPR, but for each and every site, owner needs to decide on its own: https://www.youtube.com/watch?v=-stjktAu-7k

The modern web depends on embedding third party content for many reasons, most of which have nothing to do with invading anyone's privacy and many of which are directly in the visitor's interests. It is not helpful to undermine that whole ecosystem and expect everyone to start having formal contracts in place before they can take advantage of any of those services. Nor is it reasonable to expect services offered for free that aren't doing anything shady to take on significant liability and/or other commitments anyway through formal agreements with their users. Why would they do that, instead of just (as obviously quite a few places already have) geoblocking the EU to remove themselves from the scope of the onerous rules?

To the morons (no, it is not insult, it is empirical fact) downvoting me, it is not me, it is GDPR, face the reality, it is not my fault that you are too reluctant to understand it and biting people trying to help you out wont help. Downvoting me wont change GDPR or change anything, you will just loose a valuable source of information as you did just now. Go to the first psychiatrist and it will tell you that a reality will be as it is even if you close your eyes (or shoot the messenger =/).

Don't forget to upvote me, when you figure out I was right and you get a warning/fine.

If you don't want to be banned, you're welcome to email [email protected] and give us reason to believe that you'll follow the rules in the future.