There is some controversy afoot regarding the use of latter, particularly regarding its use to refer to items in a series. Many commentators insist that latter can only be used of a series that consists of two:
We have a chicken entree and a vegetarian entree: do you prefer the former or the latter?
When presented with a series of three or more, they say, anyone wishing to highlight the last item in the series should use last and not latter:
We had soup, fish, and dessert, and the last was uninspiring.
But our evidence shows that latter is used to refer to the last in a series regardless of number:
After Ethel's action at Oxford, the ultimate sacrifice that symbolizes her self-discipline, the focus moves away to other members of her family for the latter third of the novel...
— Melissa Schaub, Studies in the Novel, Spring 2007
...I am getting crosser and snappier and sadder every minute straining and struggling to type and to read and to draw (the latter is the easiest).
— James Thurber, letter, 9 June 1939
...bee not over-power'd with policie, nor with enforcement of arguments, nor with the approach of Souldiers, and Troopers; the two first may seeme to perswade you, the latter may terrifie you into an everlasting undoing...
— A.L., To all the honest, wise, and grave-citizens of London, but more especially to all those that challenge an interest in the Common-Hall, 1648
This use is common enough that most modern dictionaries make mention of it in their definitions for latter—and indeed they should, since our evidence for this particular use is several hundred years old. Despite this evidence, however, there are still those who object to its use; if you are concerned about such things, use last to refer to the last item in a series of three or more.
