On March 16, 1994, Hammerstein would be arrested by Fred Teeven, the then public prosecutor in Amsterdam, after he suspected that his work for criminals went beyond being a defence lawyer.

For instance, he was allegedly involved in money laundering for the criminal and drug trafficker Johan Verhoek (better known as the Hakkelaar).

However, the court did rule in an obiter dictum that he allegedly acted lightly in taking on the case of Surinamese rice trader Shyam Guptar.

The subsequent investigation by the Supervisory Council (the disciplinary tribunal for the legal profession) exonerated Hammerstein from that too; the Council ruled on April 16, 1996, that "it had not been shown that Hammerstein should have doubted the veracity of what he had been told about the origin of the money and that acceptance and treatment could not be called frivolous".

Hammerstein filed a complaint against the partnership with the Netherlands Bar Association, alleging he had been treated improperly.

That year also saw the start of the Nina Brink case of internet provider World Online (WOL).

[4] In February 2014, Hammerstein published a book by Meulenhoff, "Ik heb de tijd", in which he recounts his student days at the University of Leiden, his infection with the HIV virus and his career as a lawyer.

[5] Hammerstein claims in his book, among other things, that the then prosecutors Fred Teeven and Martin Witteveen allegedly falsified evidence to arrest him in 1994.

[10][11] Hammerstein appealed against his removal on February 17, 2023, but the Court of Discipline upheld the earlier decision, making it final.