There is a huge power asymmetry between a corporation and a natural person.<p>If the former is able to voice their political opinion without constraint (e.g. Enron spends, say $1 billion dollars in an election), they can effectively manipulate our democracy, drowning out citizens' political will. This is what just happened when the (conservative) Supreme Court overturned the limits on corporate spending in political campaigns.<p>Moreover, it now enables <i>foreign</i> corporations to manipulate election outcomes.