Projects funded by German Research Foundation---teaching duties I am interested if teaching is a part of duties for people employed on the positions funded by the German Research Foundation (SFBs in particular). To the best of my knowledge, these are pure research positions. However, what is the legal status?
As far as I know, you shall not teach within your contract as doctoral researcher in a DFG funded SFB. The reason is simple: There is a project proposal and the DFG gives money to do the work that is described in the proposal. If the proposal does say that the PhD student should work on the research project (and does not say that teaching is part of the job) you shall do that and nothing else.

However, there are several caveats: This applies to all the part of your job that is funded by the SFB. It is not unusual that your position has mixed funding, e.g. 50% comes from an SFB (or another DFG project) and 50% comes from something else. You should not do any teaching in your 50% that are related to the research project, what you do in the rest of the time is another matter. I also know that it is indeed common that PhD students in DFG funded research projects actually do teach somehow (e.g. as a TA). (Probably it is worth noting that PhD students who are funded directly by the university always have teaching duties in Germany.) Maybe this is allowed under some circumstances, but I could not find any regulations by the DFG that are explicit about this. The only thing I found is this part:


  4.9.2 Eigene Stelle
  Personen, die mit einer Eigenen Stelle durch die DFG gefördert werden, sind verpflichtet, sich  mit  ihrer  vollen  Arbeitszeit  dem  in  der  Bewilligung  genannten  Projekt  zu  widmen.  Darüber hinausgehende Tätigkeiten für die aufnehmende wissenschaftliche Einrichtung (insbesondere  Lehrtätigkeiten  oder  projektfremde  Dienstleistungen  wie  beispielsweise  klinische Routinetätigkeiten sowie die Mitwirkung bei der Patientenversorgung) sind im Rahmen der von der DFG finanzierten Stelle nicht zulässig. Solche Tätigkeiten können außerhalb  der  regelmäßigen  wöchentlichen  Arbeitszeit  der  von  der  DFG  finanzierten Stelle im Rahmen des für die wissenschaftliche Einrichtung geltenden Nebentätigkeitsrechts ausgeübt werden.


This is a quote from the "Verwendungsrichtlinien" of the DFG an applies in the case where you write a proposal to fund your own position. The relevent sentence says that no teaching or non-project related service is allowed.