In principle, an AD is a State of Design AD when the authority that issues the AD is, on the date of issuance of that AD, the State of Design authority for the products, parts or appliances (or STC modification) to which the AD applies. The Type Certificates of some products have been known to move from one State of Design to another in the recent past, e.g. the Bell 206 and 222 helicopter types moving to Bell Helicopter Textron Canada, from the USA to Canada; the British Aerospace 125 business jet type design was sold to Raytheon (now Hawker Beechcraft Corp.), moving from the UK to the USA; and APEX sold the R 2000 type design to Alpha Aviation, moving the State of Design (responsibilities) from France to New Zealand.
When operating a product for which France is the State of Design, e.g. an Airbus aeroplane, or a CFM56 engine, the applicable ADs are those issued (or approved) by EASA and, previously, ADs issued by DGAC France.
When operating a product for which the USA is the State of Design, e.g. a Boeing aeroplane, or a General Electric engine, the applicable ADs are those issued by the Federal Aviation Administration (FAA).