If you have atleast a two years of legal experience OR a second bachelor/master degree (other than your first degree of law)--you have a good chance of getting into one of the Ivy Leagues schools! I have seen many real life cases verifying that.
For schools other than the Ivy League schools, your B grade will get you in even without work experience and a second degree, provided you have a required TOEFL score (if English is not your native language) and you have a strong Personal Statement.

I hope this was helpful!

The admission process takes into consideration many things, not only the grades. Your School, your professional experience and your awards or publications, all counts. Columbia, Georgetown and NYU have huge programs and therefore it is not so difficult to be admitted in these schools if you attend the requiments (top school in your country, reasonable grades, good professional experience, some publications).