"Issue advocacy ads" support or oppose particular policy positions or candidates. But because issue ads never explicitly urge the public to vote a certain way, a 1976 Supreme Court decision deemed them "non-political," exempting their funding from regulation.

Issues ads became a significant campaign tool in the 1990s, when some groups – led by those advocating terms limits and some on the religious right - began aiming ads at specific candidates. Other interest groups and the major political parties followed soon after, and issue ads now rival soft money as the primary source of unregulated campaign funds.

By avoiding such "magic words" as "vote for," "elect," "cast your ballot for," producers of these ads can legally conceal their identities, as well as the funding sources and the amounts of money spent. Corporations, industry associations, political parties and individuals may spend as much as they please on issue ads, which often closely resemble and complement ads that candidates fund themselves.

Adding to the confusion, corporations and industry associations often disseminate their advocacy messages through affiliated organizations. The Environmental Working Group (EWG) has compiled a list of groups that promulgate messages friendly to the chemical industry.

Environmental Working Group (EWG) Web site.