Is Romer's letter on our search for the elementary proof of the spin-statics theorem out of date today? The following link provides a letter to the editor by Robert H. Romer who writes, 

In a 1994 "question" in this journal,
  Neuenschwander asked whether anyone
  had yet met Feynman’s challenge of pro-
  viding an elementary proof of the spin-
  statistics theorem... In spite of the importance of the spin-
  statistics theorem and the attention that
  has been devoted to it, the physics commu-
  nity still waits—probably in vain—for an
  elementary proof.

I currently face mixed answers on our understanding of the elementary proof of the spin-statistics theorem. Romer's letter suggests to me that we still do not fully understand how to prove the spin-statistics theorem from first principles. Does Romer's letter still stand true today, or has there been a recent publication that outdates Romer's letter?
 A: Your question appear a little confused to me: A proof of the spin-statistics theorem certainly exists, and it has been known for a long time that this is, indeed, a theorem and not a conjecture, see e.g. here, or any thorough book on quantum field theory (such as Peskin & Schröder) for proofs. It was first proven in 1939 by Fierz, and later elaborated by Pauli. The proofs are not handwavy and certainly deserve the qualifier 'from first principles': There is no issue there.
Another question entirely is whether a simple proof of the spin-statistics theorem exists. It is not completely clear what this is meant by this, but I assume that either Feynman or someone else stipulated some criteria which any such proof should satisfy. In particular, I suspect that the simple proof is required to abstain from employing methods from quantum field theory or advanced mathematics. It is not clear that such a proof exists, and none have been found up this moment, as far as I know. So, in short, Romer's statements are not outdated, but the spin-statistics theorem has been proven.
