I figured I'd RI a topic near and dear to my heart, campaign finance reform.

Here's the opinion piece in question. I'm only RIing the section titled "Contributions are not bribes", since I don't have the knowledge to comment on the rest of the piece.

The OP's argument (if you couldn't guess) is that political donations do not influence the behavior of elected representatives in any significant way. The OP makes repeated appeals to scientific evidence, although references are very scarce, making it difficult to validate his claims.

One common concern is that legislators adopt positions based on the expectation of reaping future contributions. So it remains possible that special interest financing and lobbying exerts strong influence over the content of public policy.

But scientific evidence for this claim is also weak. Several studies examine the share prices of politically active firms before and after major changes in campaign finance law and find no smoking gun.

Since the studies in question aren't referenced, it is difficult to take this claim seriously. However, even if politically active firms didn't see changes in share price before and after legal reform, this could simply be because the reforms in question weren't effective.

Regardless, there actually is evidence that politically active firms do have persistently higher stock prices. I couldn't find the original research in question, but this article from The Economist details the somewhat infamous "Lobbying Index", whereby firms are weighted by their lobbying expenditures relative to their total assets.

In aggregate the results have been stunning, comparable to the returns of the most blistering hedge fund. The [lobbying] index has outperformed the S&P500 by 11% a year since 2002 (see chart). There have been bumps along the way: the index fell sharply in 2008 and again this summer, when debt-ceiling brinkmanship raised the prospect of government austerity. But at other times, it seems remarkable that companies would do anything but lobby.

Now, this certainly isn't a "smoking gun" that lobbying influences political decisions, but it does suggest that political donations provide a handsome return on investment, presumably by influencing legislator's decision making.

On with the RI.

One would expect that if a firm could buy tax breaks or favorable legislation, then recent Supreme Court decisions upholding prohibitions on corporate soft money contributions to parties, or later, permitting corporate independent expenditures, would dramatically effect profitability and would show up in big stock price movements. But that is just not the case.

Again, the lack of citations make it difficult to take this claim seriously. However, if SCOTUS struck down regulations that were ineffective in the first place (as was arguably the case with Citizens United), then the stock price of politically active firms would be unaffected by the decision.

Interestingly though, there is evidence that companies can lobby for tax breaks that are relatively quite generous. Whether this specific behavior constitutes rent-seeking is up for debate, since lowering the corporate income tax is considered ideal by most economists and policy experts.

However, this paper provides evidence that prior to the 2008 financial crisis, lobbying from mortgage-lending companies helped in creating both a more lax regulatory environment, and increased the probability of receiving bail-out money after the recession.

Either way, the OP is incorrect in his claim that lobbying doesn't influence legislators' decision making. Given the expense associated with lobbying, it would be hard to imagine a situation in which political donations were made without an expectation of reward, especially from profit-maximizing firms.