They are under the legislation of the country they operate out of, in this case the Netherlands.
If you are a Dutch company, you have to obey Dutch law.
They may be a multinational company who operate in several countries, and have to obey local laws in those countries, but ultimately how the company is governed and under which legal framework they are judged is Holland, where they pay their tax.
Shell are a reputable company and choose to be Dutch. It gives them a lot of advantages, and a few disadvantages.