"Money is the mother's milk of politics," said the late Jesse Unruh, speaker of the Californian State Assembly in the 1960s.

That maxim was, is and will continue to be true.

And when state and federal legislatures enact rules designed to control the structure of campaign finance, voters should be aware that this is akin to sending foxes to guard the henhouse.

At bottom, infighting between the major political parties over the rules controlling the flow of campaign finance and the many ways money can be spent to influence campaigns is aimed at gaining an advantage for one side or the other. Such an advantage may be only temporary, but it can be decisive in any given campaign year.

The ongoing scandal over the Internal Revenue Service's one-sided harassment of conservative non-profit "social welfare" organizations in 2012 is a fresh example.

On numerous occasions since the first modern effort to control campaign finance, the Federal Election Campaign Act of 1971 and its 1974 amendment, federal courts have been called in to define the bounds of legislative attempts to set limits on campaign contributions and expenditures.

Like every previous decision finding that congressional limits must not violate the First Amendment's guarantee of free speech, the Supreme Court's latest decision has generated heated accusations that the tables are being tilted to favor deep-pocket influence seekers.

There are now three main streams of political finance. On April 2, the high court addressed the rules governing so-called "hard money" that can go directly to candidates and is subject to tight regulations. In 2010 it addressed the realm of "soft money" spent by independent individuals and corporations to influence elections, holding that restriction on such spending in the weeks before an election was an infringement of the First Amendment. Both "hard money" and "soft money" contributions must be disclosed.

And in the long run, such disclosure remains the best way for the public to "follow the money" in American politics and make better-informed choices as a result.

However, the Supreme Court has yet to address the questions raised by "dark money," funds spent on political activities by tax-exempt organizations that do not have to disclose their donors. The IRS controversy involves a renegade effort to limit such spending by conservative groups.

The current Democratic Party line is that "dark money" being spent secretly to influence elections comes mainly from the Koch brothers, billionaire industrialists who support a number of conservative organizations.

The Center for Responsive Politics recently suggested that some $86 million in 2013-2014 dark money - about one dollar in four - can be linked to the Kochs.

But the same organization also reported that groups supporting liberal causes were responsible for about 70 percent of "dark money" being spent on the 2014 election campaign, as of late last year.

The same watchdog group has also compiled a list of "heavy hitters," organizations and individuals who have been the biggest political campaign contributors over the past 25 years.

Of the top 15 names on this list, labor unions account for ten. Total contributions to the Democratic Party from the top 15 political contributors from 1989 to 2014 were $529 million, while Republicans got $108 million. Koch Industries was listed in 59th place, with contributions of about $17 million to Republican causes.

Bear those numbers in mind the next time Senate Majority Leader Harry Reid, D-Nev., himself a prolific fund-raiser, calls the Koch brothers "un-American."

Bear in mind, too, that full disclosure of all political contributions should be the first goal of meaningful campaign-funding reform.

But remember that with each change in campaign finance rules, big-time contributors find new ways to donate big money to the candidates and causes of their choice.