Back in the 1950's, I believe, there was a Supreme Court ruling on what non-people, i.e. organizations, specifically corporations, can donate to political campaign spending. After the ruling, the a justice was asked, officially off the record, about the ruling, and dropped a line that was equated as "corporations are individuals, with the same free speech rights as other citizens, and spending ad money is free speech".
That spurious anecdote is certainly an inauspicious way to start an explanation, but I honestly can't remember the details. I really should have it written down. I can't find the story again right now, because Google is absolutely overwhelmed with results for any combination of "corporation" "supreme court" "free speech" and "campaign spending". Why, you ask?
The Supreme Court Ruling on Citizens United v. Federal Election Commission - There is no limit on the amount of money that may be spent on unorganized political advertising, by corporations or any other people.If you go and look it up, you'll find hundreds of blogs and minor news sites crying about the sky falling, and a handful of other sites calling the rest ninnies. I'm not exactly of either camp, but I can try to explain both. For non-Americans this is largely meaningless, but when you have to seal yourselves underground in twenty years, this might help explain why. The first thing to understand is that federal campaign financing laws are a cthonic mess of regulations and stipulations, the remnant of a hundreds years of bloody battles between extraordinarily brave politicians trying to limit where and how campaign money can be spent, and essentially the entire rest of government. I could never possibly explain the entire system even if I knew it, but in a nutshell - if you want to donate money out of pocket directly to a campaign, every individual American citizen over 18 can donate up to $2300 to each specific politician's campaign account and each specific party account. For example, if you wanted to donate as much as you can to (hypothetically) get Ralph Nader elected, you could give $2300 to Ralph Nader for President and $2300 to the Green Party, and that's it.
However, (you knew that was coming,) there are these things called "Political Action Committees", essentially just formalized clubs (they do have an actual legal registration, but there's no real limit on who can make one and how they can operate) who can take donations as from people, and then spend it on political campaign advertising. The trick is that no matter how strongly they declare their allegiance to a party or politician, and they all do, as long as they're not directly run by the campaign itself, they can spend whatever money they want, as per the money=speech idea.
This has been the de facto way for corporations (who, remember, supposedly hold the same legal status as people) to spend unlimited money on political campaigning. I'd be remiss if I didn't also mention the same applies to unions and other special interest groups, but let's not fucking kid ourselves on who has what kind of money to spend. What this ruling basically does is formalize the idea that non-humans can spend as much money "out of pocket" as they can afford just like humans, and removes the necessity of an extra step of bureaucratic transparency. Whether or not that will actually make it harder to see where and who campaign money comes from and when and how it's spent, we'll just have to wait and see. So, it's meaningless in terms of the practical effects of financing law, but it does signal an incredible change of tone, that the harsh political campaigning laws of the 1950s have finally been rolled and defanged back to the free reign of the 19th century, with my spurious anecdote finally enshrined in common law.
The ruling is also a chilling if completely expected window into the mind of the Supreme Court. Bush-appointed Chief Justice John "Leave It To Beaver" Roberts, who has the responsibility of decided what appeals the Court will hear, and is the currently youngest member of a lifetime appointment, defined himself along with Samuel Alito with "legal precedent always takes precedent no matter what". They've now both signaled that, just as anyone could have guessed, they're perfectly willing to overturn any precedent they don't happen to like. How far that will extend to other matters, only time can tell.
You can read all the briefs and analysis you ever wanted at ScotusWiki, the semi-official wiki of the U.S. Supreme Court.