The UK High Court (despite the name, it's two layers down from the highest court: the House of Lords) has held that the sale, advertisement, possession for commercial purposes and use of PlayStation 2 modification chips is illegal in this country.
This is a direct consequence of the UK passing legislation implementing the European Union Copyright Directive (EUCD), which contains a copyright anti-circumvention provision similar to the DMCA. The EUCD's implementation has given Sony the legal teeth to pursue PS2 modders across Europe.
The EUCD is very controversial and its passing and implementation has been the subject of protest in many countries across Europe, since it is perceived to be the European equivalent of a failed and flawed US law.
Despite the EUCD, an Italian court has ruled that PS2 mod chips are legal and Spanish law also has a loophole which allows them.