How does reciprocity work in Canada? In Pakistan, I am called in Punjab, but through agreements, I can appear before all Courts and Tribunals (except the SC, which has its own rules). Usually, there is no need to do anything except simply provide proof of call; and laws can be very different.
I’m a practising lawyer in Ireland (South). I had to learn British (mostly England and Wales) law to the extent that it was relevant to Irish law… which is a lot. We also learned a number of cases from other common law jurisdictions, cases in which a principle was established that has been widely accepted in the common law world. And of course, EU law.
For solicitors (I’m not sure about barristers) the education process now includes a mandatory class on English and Welsh property law, which entitles us to register to practise in England and Wales. I can also register to practise in the North of Ireland without needing to undergo any testing or any additional courses. But not Scotland.
One of my colleagues was educated in Spain, but is able to practise in Ireland because of EU law on mutual recognition. He is however prohibited from practising in certain areas of law that were not part of the Spanish curriculum.
I was wondering that too.
In the US, lawyers can generally appear pro hac vice for a limited number of cases (say, two or three a year) in states where they are not licensed, but that’s it. Any more than that and you have to apply for full admission to that state’s bar.
In some cases, there is full reciprocity between states and if you’ve been licensed in your home state for five years all you have to do is fill out an application and pay an admission fee, plus yearly dues. For others (sadly including Florida) there is no reciprocity at all. To be admitted in Georgia, I would have to take the Georgia bar exam and submit to a full character and fitness investigation.
My post had nothing to do with the law aspect of the OP, it was a comment of agreement with and expansion on the example used of needing to know some physics in order to understand chemistry. I was talking about science, not about law. (I majored in biology.)
And this illustrates the second sentence of my observation exactly:
QED
[/hijack]
Y’all can go back to talking about law now. 
Science isn’t really a good analogy for legal education, because the primary goal of a law degree is to enable you to practise law: and law is geographically specific, since it is an entirely artificial construct.
In my opinion, there is a real benefit in knowing about other legal systems, to get context and an understanding of law as a discipline, but if your goal is to practise law in a particular jurisdiction, knowledge of other legal systems is generally not needed.
I’m on the road at the moment and don’t have much time, but will get back to this in a few days.