The Madrid train bombings can also be seen as proof that the current data retention level is sufficient and hence the EU directive is not necessity.[citation needed] Schemes for data retention do not make provisions for adequate regulation of the data retention process and for independent judicial oversight.[citation needed] Data retention is an invasion of privacy and a disproportionate response to the threat of terrorism.[citation needed] It is easy for terrorists to avoid having their communications recorded. The Home Office Voluntary Code of Practice of Data Retention admits that there are some internet protocols which cannot be effectively monitored.[citation needed] It would be possible for terrorists to avoid monitoring by using anonymous P2P technologies, internet cafés, anonymous proxies or several other methods. Some police officers in the EU are sceptical about the value of data retention.