User blog comment:Calvincambridge30/Versus/@comment-3481504-20151019145014/@comment-26982641-20151019154536

You are right about something. God's Law. It's never mentioned but Raphael who never cares about mankind could use all of the souls in the heaven but he didn't. God might forbid that kinda things. Also Cas said Raphael cares about traditions so as Samandriel said we are their guardian not their gambler, he might only cared about this view.

Second, In Season 8 Episode 12 Sam and Henry Winchester had a speech:

-Tapped in your souls power? I thought only angels can do that. While we saw Angels had no souls but they were able to use any other soul's power, we learned that human can only use his own souls power in a limited degree (spell casting, others unknown) and as Sam said he did not think demons are able to use souls' power. (Just for deals)