User blog comment:Hidden Sniper/Mechanics that don't make sense to me - Part 1 Lifesteal/@comment-4922088-20130716224611/@comment-4814368-20130716235302

I also think it would be neat and make sense of life steal did not return health for damage dealth to shields. Meaning if a champ did 300 dmg to someone with a 200 hp shield, the percentage of life steal or spell vamp  would only return hp based on the 100 damage dealt.