Suppose Alice is a customer of a business ACME who holds data on her like email correspondence. ACME uses a third party to manage their email, suppose Fastmail.fm. Fastmail.fm in turn delegates their data storage to a fourth party like Amazon’s AWS or Microsoft’s Azure, or to make it even more fun, perhaps Snowflake stands in between Fastmail and Azure.

Can Alice SAR any of those entities for her correspondence with ACME, or only one or some of them?

1 Answer 1


Not in the example

Alice is a customer of ACME. ACME is the Data Controller. ACME contracts Fastmail as a Data Processor.

Data Processors are different from Data controllers.

Yes in general

Let's say Alice is a customer of Amazon Prime and watches Twitch. The accounts are linked. Twitch and Amazon are joint Data Controllers on some data (though one is a subsidiary of the other).

Now, Alice links her account for a game. Both Amazon/Twitch and the game now are both data controllers on some data (usually: user name on both platforms and some kind of ID are shared), but they don't share all data either has.

The game and Amazon as well as Twitch are Data Controllers, each with different data amounts and in some cases, jointly administring some data.

  • 1
    I don't think there are joint Data Controllers in your example. Both entities have a copy of the same data and each of them is responsible for appropriately handling it.
    – quarague
    Apr 16, 2023 at 1:05

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