The EU is to take France to the European Court of Justice and has sent Germany a "reasoned opinion" that it has broken European law.
Should Bonn fail to give a satisfactory reply within two months, the commission could launch a second case at the European Court, which can force member states to adopt EU policies.
Brussels claims that France has failed to implement a 1988 directive establishing cross-border recognition of higher-education diplomas awarded after three years' professional education and training.
This law is intended to enable professionals such as teachers to switch to jobs in any EU country they choose, with a minimum of bureaucratic interference. Member states should either recognise qualifications gained in other EU countries immediately, or set up an aptitude test that enables the authorities to decide what extra training a professional might need to start work.
France is refusing to implement the system for primary teachers, who are considered by Paris to be civil servants and so beyond the scope of the directive.
Instead, anyone wishing to become a primary teacher in France has to take the competitive examination set for French nationals and an additional training course before receiving their teaching diploma. The commission says teachers should be treated as professionals, not civil servants.
Bryan Peck, former chairman of the European Association of Teachers, said the limited mobility of professionals in the EU fell far short of the aspirations of the Treaty of Rome; from 1988 to 1994, only 5,000 EU teachers had their qualifications recognised in another member state, the majority of them in the UK.
Mr Peck added: "It's a problem for teachers to find work elsewhere in Europe and it's going to get increasingly difficult as the EU enlarges, with east Europeans trying to find work in the West."
The German case involves Bonn's non-recognition of teaching qualifications gained after less than three years of study, including certificates of education granted in the UK before teaching became a graduate profession.
The commission claims that this contravenes Directive 9251EEC which orders the mutual recognition of such qualifications gained across the EU.
Under its terms, member states should accept these qualifications, even if- as in the UK - national rules insist that training should last at least three years. If they do not, teachers should be offered time to complete extra study or the chance to take an aptitude test.
Germany has refused to comply, hitting the rights of a number of British teachers and a larger number of Austrian teachers, who studied for just two years.