With Certain Exceptions It Is Not Legal To Posess A Narwhal Tusk In the United States

Chef Lukasz has been released from hospital. Yay!
From A Crime A Day:

16 USC §§1372(a)(3), 1375 & 1362(6) make it a federal crime to possess a narwhal tusk, but not if it's for "enhancing the survival of a species."https://t.co/AJMzBC4dqZ

— A Crime a Day (@CrimeADay) November 30, 2019

Via Ogilvy's Vice-Chair Rory Sutherland.

And (somehow, in an addled mind) relatedly:
Santa and CFR › Title 25 › Chapter I › Subchapter J › Part 243 › Section 243.4