[College Repub]

What does American law matter in any of those countries?

[TheAngryClam]

When you're the world's economic powerhouse that nearly every country on earth sends goods too, and many multinational corporations have operations in, a familiarity with U.S. Customs, Immigration, Taxation, and particularly Contract (since many U.S. firms demand a "choice of law" clause that stipulates American commercial law apply to disputes) law are important fields to be familiar with.

Same reason that having some familiarity with Chinese, Japanese, or EU law is useful for many American attorneys.