i'm pretty sure, since it came out in a white dwarf, They are chapter approved. And anything chapter approved is okay
It all depends on the tournament. At my local hobby shop tournies they are not aloud. At Games Day they aren't aloud either, so im guessing that at your tourny they are probally not allowed; although, they could be. I'd ask the manager of the store or whoever is running the tourny to know for sure.I was wondering whether it is legal to use a harlequins army list at a tournament since they dont actually have a codex just a pdf file on the GW site.