Lately, there has been an expansion phenomenon in the use of DNA techniques in criminal investigation. Several of our European neighbouring countries are undertaking reforms in this area. However, the proliferation in the use of DNA is hindering a series of guarantees that up until present were considered settled. The exceptions to the judicial due process is an evident example of this trend. Examples of this can be seen in the last interpretation that the Supreme Court has made of the Spanish regulation and the last reform in Germany, both of which we will take a look at.