Yikes. I heard the the same refrain "it's illegal to force you to make a decision before April 15" from a Yale MPHer that I met at an interview day. It appears that it's not about legality, but it's a friendly agreement that Council of Graduate School members have entered into : http://www.cgsnet.org/Default.aspx?tabid=201 , and clearly is more of a guideline than a rule since I have been given deadlines earlier than April 15 by multiple reputable schools/departments.
I am in the same boat (one wants to know by March 1...less than a week after their visit day - eek!). In the professional world, if you accepted a job, and then continued to interview for other jobs, it would reflect really poorly on you (my current office - at NIH - actually pulled a job offer last year because the person accepted and then continued to interview). The public health world is SMALL so you really need to think about whether accepting a school's offer and then backing out could have any negative consequences, especially if your potential advisor (who is pulling strings to get you funding at many SPHs) might hear. I think the best way is to be honest, and explain to the school that they are at the top of your list but you want to make an informed decision and need another week or two.
That said, I wish I could just hear from everywhere by March 1 then decide and have it be over!!! Good luck everyone
