Depending on context, yes. In a list where all items are the same
level, a comma before 'and' is poor grammar, albeit not necessarily
'wrong':
My bag contains juicy apples, pears, oranges, and lemons.
should be
My bag contains juicy apples, pears, oranges and lemons.
or
My bag contains juicy apples, pears and oranges, and rotten lemons.
(In the original, inserting the comma introduces an ambiguity about
whether the lemons are juicy. This ambiguity is exploited in en_GB
marketing but that usage doesn't validate the poor use of grammar when
the writer is not trying to deceive the reader. Note the extra 'and'
added prior to the comma in the alternative.)
Where there is grouping within the list, a comma can be used:
My bag contains juicy apples, pears and oranges, and vegetables.
(Again another 'and' has been added. Most people would not describe
vegetables as juicy so the ambiguity is not present and the comma
indicates the break in the descriptive list.)
--
Neil Williams
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