So Western karma and Buddhist karma can be a bit different, as the West has adopted the term it's become the Western version of the idea. And Buddhist karma is a bit different from Hindu karma. I haven't found a fully consistent use of the word across Buddhism even. But one common theme is that you shouldn't be ascribing the suffering of others to their karma.
Soto Zen view:
" We say, result is—will result immediately, not later punishment. To do something is already punishment. That you do something is already punishment. Not later." (edit: I may be taking this out of context....)http://suzukiroshi.sfzc.org/dharma-talks/october-1968-9th-ta...
Overview: http://en.wikipedia.org/wiki/Karma_in_Buddhism
Theravadan view: http://www.accesstoinsight.org/lib/study/kamma.html
Soto Zen view: " We say, result is—will result immediately, not later punishment. To do something is already punishment. That you do something is already punishment. Not later." (edit: I may be taking this out of context....) http://suzukiroshi.sfzc.org/dharma-talks/october-1968-9th-ta...
Secular view: http://www.stephenbatchelor.org/index.php/en/karma-and-its-f...