This is one of those situations where split will help you to leave your sanity intact. Assuming your subjects are always comma delimited, with a possible & or 'and' as last separator:

use strict;
my @subjects=("camel, flea, humbug, hubris", "Camel, Flea, Humbug & Hu
+bris","CAMEL, FLEA, HUMBUG and HUBRIS");
for (@subjects) {  
  my @elements=split /\s*,\s*/;
  push @elements, split /\s+&\s+/, pop(@elements);
  push @elements, split /\s+and\s+/, pop(@elements);
  print join "\n", @elements;
  }
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Note that the whitespace handling in the seperators above is a bit crude, but hey, it's just example code :)

Update: Must have more coffee ... see dingus' post below for a split that does it all in one go. Then again, that brings you right back in regex headache land, so YMMV.

CU
Robartes-