In the phrase attorney general, attorney is the main part, and the word general is descriptive—it tells us what kind of attorney we have to deal with.
Believe it or not, I wrote this segment last week, before all the news about the attorney general broke, because I kept hearing people talk about all the state attorneys general.
For my listeners who aren’t in the US, the nation has one federal attorney general, but each state also has its own state-level attorney general. And I was really pleased because most people were making attorney general plural the right way—by making the word attorney plural.
The US has one attorney general, but we have many state attorneys general.
In the phrase attorney general, attorney is the main part, and the word general is descriptive—it tells us what kind of attorney we have to deal with. It’s the same rule we follow for similar phrases such as sister-in-law and editor in chief. You make the main noun plural:
I have two sisters-in-law.
Congratulations to all those news writers who have been getting the plural right recently.
Note: In British English, attorney-generals is also acceptable according to Garner’s Modern English Usage.
What Is the Plural of 'Deputy Attorney General'?
Update: After the podcast aired, we got an interesting follow-up question: What is the plural of deputy attorney general?
Although I couldn't find an answer in a style book, my gut instinct is that it would be deputy attorneys general because attorney is still the main noun and deputy is a modifier. When I can't find an answer in a style book, sometimes I search major newspaper websites to see what they use, and it looks like my instincts are right: the New York Times highly favors deputy attorneys general.