When Smithfield Foods CEO Larry Pope appears before the Senate Agriculture Committee this week, senators will likely grill him on whether U.S. consumers will be harmed by the proposed $4.7 billion sale to the Chinese firm Shuanghui. Some members of Congress have suggested the deal could hurt the U.S. food supply, even though the meat will be exported.

It seems probable that the deal will go through, but one hurdle is that it must receive approval from the little-known Committee on Foreign Investment in the United States (CFIUS). As foreign investment rises CFIUS, the federal committee created by President Ford that is barely known outside Beltway and M&A circles, will only become more central to investment by foreign firms. CFIUS’s opaque rules will reach even further into deals from candy companies to technology portals.

For the past few years, international interest in American companies has risen dramatically. Dealmakers in China, Russia, Japan, Europe and elsewhere are snatching up U.S. firms, real estate and other assets. In 2013, the U.S. claimed first place on the Foreign Direct Investment Confidence Index after dropping to fourth last year. And as the global economy continues to recover, overseas investors will be spending more cash on mergers and acquisitions — from New York to Houston.

CFIUS reviews are also on the rise. According to CFIUS’s Annual Report to Congress, the number of notices increased from 65 in 2009 to 111 in 2011, though this was in part a function of the recession. The number of CFIUS investigations has risen from 6 in 2007 to 40 in 2011. These inquiries into more concerning transactions are supposed to last 45 days, but some go on for months. Asia is particularly sensitive. Since 2007, CFIUS reviews of deals involving Chinese firms have tripled. Reviews of Japanese firms have increased sevenfold.

Despite this boom, CFIUS divulges little guidance or know-how to lawyers and companies navigating the regulatory swamp. No opinion is ever explained. Neither is inaction. And companies can’t challenge a CFIUS decision. That may have been understandable when foreign investments were limited and Cold-War-era concerns were at work. Even though there are still serious national security issues, now that global business currents are inextricably tied to the U.S. economy, the committee’s unwieldy structure and lack of transparency threaten to harm U.S. business interests by delaying deals and holding back investors from bidding, which lowers U.S. investment dollars.