In Germany basically everybody can be pierced, who has turned 18.
In the age from 7 to 17 a written compliance of a parental unit must be available. Many serious studios refuse the piercing by persons under 14 years completely.
There isn´t any well-defined law. which pretends who among whom qualifications may pierce. In the bygone years there was different rudiments again and again, but none could prevailed proper, was changed again or even revoked completely. So for example in 1999 the constitutional court in Gießen (Germany) has passed, that a piercing may stitched only by persons with appropriate knowledge (qualification for alternative practitioner etc.). In 2000 this law was changed and now it only applies to piercing with local anaesthesia.
In April 2008 started a law initiative, which demands the strict prohibition of body modification by minors. Certainly it isn´t passed not yet.