To obtain a passport through deception or to use a passport issued to another is a crime. The most common practices are substituting a page with a legitimate visa into a passport without a visa, substituting a photograph on a stolen passport and stamping a forged visa on a passport.
In one instance, a Portuguese consul stole 2000 passports which he sold to wealthy Chinese who used them to enter the EEC/EU as Portuguese citizens from Macau. Officials believe that a high proportion of the 50,000 Dutch passports that go missing each year end up with forgers.