Safe Harbor Overview
We have chosen to comply with the principles of the Safe Harbor Framework developed by the U.S. Department of Commerce in consultation with the European Commission and the Federal Data Protection and Information Commissioner of Switzerland, except where limited by any legal, regulatory, ethical or public interest considerations. More information about the principles that make up the Framework, as well as other frequently asked questions relating to Safe Harbor can be found at: http://www.export.gov/safeharbor.
In the linked page it states that (emphasis mine):
On October 6, 2015, the European Court of Justice issued a judgment declaring as “invalid” the European Commission’s Decision 2000/520/EC of 26 July 2000 “on the adequacy of the protection provided by the safe harbour privacy principles and related frequently asked questions issued by the US Department of Commerce.” According to that decision, the U.S.-EU Safe Harbor Framework is not a valid mechanism to comply with EU data protection requirements when transferring personal data from the European Union to the United States. Please note that, pursuant to the Safe Harbor Frequently Asked Question on Self-Certification, the commitment to adhere to the Safe Harbor Principles is not time-limited, and a participating organization must continue to apply the Principles to data received under the Safe Harbor.
On July 12, U.S. Secretary of Commerce Penny Pritzker joined European Union Commissioner Věra Jourová to announce the approval of the EU-U.S. Privacy Shield Framework, which will replace the U.S.-EU Safe Harbor. Secretary Pritzker announced that the Department will start accepting certifications on August 1st.
As of August 1, the Department of Commerce will stop accepting new submissions for self-certification to the U.S.-EU Safe Harbor Framework. As of October 31, the Department will stop accepting U.S.-EU Safe Harbor re-certifications. The Department will maintain the U.S.-EU Safe Harbor List of participants.
Please note that this advisory does not apply to the U.S.-Swiss Safe Harbor Framework, which the Department will continue to administer.
For more information on the EU-U.S. Privacy Shield Framework, please visit https://www.privacyshield.gov .
It has been already a year since the resolution of the European Court of Justice, and I haven't heard of any change.
What is doing Stack Exchange to ensure my privacy as an European user under the Privacy Shield?
About Privacy Shield (again emphasis mine):
The EU-U.S. Privacy Shield Framework was designed by the U.S. Department of Commerce and European Commission to provide companies on both sides of the Atlantic with a mechanism to comply with EU data protection requirements when transferring personal data from the European Union to the United States in support of transatlantic commerce
See the new requirements.