Thanks y'all for mentioning the IEEE as an example. It's a great illustration of how the "exclusive memberships" category works (and doesn't work).
Preface: The "membership in associations that require outstanding achievement" category is, interestingly, one of the hardest to satisfy. Adjudicators are trained to focus on minute details of the organization's criteria for membership, and the extent to which they're governed by "recognized experts" in the field.
This has resulted in some incredible nit-picking by USCIS about how "outstanding" you have to be, to qualify for membership, and who chooses you.
In general, organizations that require only a degree (even an advanced degree), or the payment of dues, don't meet the criterion.
The highest tier, "Fellow," "recognizes unusual distinction in the profession and is conferred only by invitation of the Board of Directors upon a person with an extraordinary record of accomplishments in any of IEEE’s designated fields of interest."
THAT is exactly what USCIS is looking for, and it definitely meets the criterion.
The second tier, "Senior Member," "is the highest for which application may be made and requires experience reflecting professional maturity." This level requires that "the candidate shall have been in professional practice for at least ten years and shall have shown significant performance over a period of at least five of those years, such performance including one or more of the following: [list of major professional accomplishments]."
I'd argue that this "Senior Member" tier is also an "exclusive membership," because of all the ways it requires "outstanding achievement" of its members at this level.
All the other levels of IEEE membership are non-exclusive, and I wouldn't bother including them, as they would weaken your case.
Unless something has changed very recently, you do not have to have a Ph.D. to be an IEEE member.
Source: long-time IEEE member without a Ph.D.