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i'm doing the summer associate thing at a big firm in a fairly big market (not a secondary market), looking to switch markets. ideally my firm would let me switch to its office in the other (also primary market) city. if not, i'll be applying to other firms.

questions:
1. do i ask my firm before or after i (hopefully) get an offer.
2. when talking to people at other firms - do I tell them where I work now/ will they tell my firm? / what do I do about that?

thanks!

Know multiple people who have done this.

On other firms: Everyone in law understands that recruitment is premised on confidentiality. Everyone in biglaw when switching firms is at another firm. Your firm you are currently at is interviewing laterals from other firms. Everyone gets that this system cannot work without the utmost regard to confidentiality.

You should not ask your firm until you have a firm offer in place from another firm. You should accept your firms offer and then bring this to the table only after you get the other offer. I assume for you that this job is better than no job. Do not risk it until you have some cards to play.

I my firm I know of people who did it both before and after they had an offer. It'll probably depend on:
1) Whether there is room for you in the other office (do they need you? does the work you do/want to do exist there, etc.) How big is your summer class? How big is the class where you want to go?
2) What are your reasons? Common sense will tell you that the more relatable your reasons are, the more people will understand. FWIW both people I know of did it for personal/SO reasons.
3) How you communicate it: If you say (and come off as genuine) "I'm very excited to be working for Smith&Jones LLP, I really want to start my career here, but I have this issue..." You'll get better responses that "If you don't let me, I'm going somewhere else"

I'd ask any associates you've gotten to know for advice on how the firm will view it.