The USA's President Trump has announced that the country is "terminating our relationship" with the World Health Organization. But I haven't been able to find any information on what the legal consequences of such an action are. The WHO constitution lays out the process for joining the organization, but not for leaving. Can the US be said to officially no longer be a member, or is this some unprecedented legal gray area where there's no formal definition of what it means to be a non-member?
The law regarding US membership in the WHO is 22 USC Subchapter XX. 22 USC 290 states that "The President is hereby authorized to accept membership for the United States in the World Health Organization", and 22 USC 290a empowers POTUS to appoint delegates. 22 USC 290c directly addresses withdrawal:
In adopting this subchapter the Congress does so with the understanding that, in the absence of any provision in the World Health Organization Constitution for withdrawal from the Organization, the United States reserves its right to withdraw from the Organization on a one-year notice: Provided, however, That the financial obligations of the United States to the Organization shall be met in full for the Organization’s current fiscal year.
The law does not state exactly how it is to be determined that the US has exercised its right to withdraw. On the assumption that POTUS has the power to do so unilaterally, it would be effective a year after the US has officially withdrawn. There is no official presidential order to this effect at present, so we will remain members of WHO until at least 5-31-2021.