Contributions to Politicians and PACs and Special Interest Groups

I was thinking about how corporations make these contributions to promote their interests, and it is fundamentally on a different scale from contributions from civic groups. When an individual makes a contribution to a PAC, the money comes out of his or her salary, but a corporation makes contributions on behalf of its employees, and it comes out of all their salaries. However, the employees themselves have no say in this. My friend was telling me about fiduciary duties, which may present a legal framework for corporate actions. Perhaps I'd be interested in reading more about corporate law.