I can’t make this stuff up: the active ingredient for heparin, the blood thinner drug, comes from pig intestines. The Wall Street Journal’s Web site has a, well, memorable photo of a worker with his hands about to reach into a shiny pile of them on a table. Like I said, I can’t make this stuff up.

Heparin, of course, is the subject of a progression of FDA alerts, company recalls, and red faces when it became known that some patients getting the drug experienced allergic reactions, some of them severe enough to cause death. The Wall Street Journal photo, it turns out, might be apropos for the messy litigation to come. And come it has, not as the flood of complaints as in drug mass torts past, but in a trickle. Depending on which column you read in a recent FDA statement, there are either 81 or 131 deaths from patients taking heparin between Jan. 1, 2007, and April 13, 2008.

Right off the bat there could be a high causation hurdle for litigation. For example, heparin’s often given to kidney dialysis patients, so they’re sick to begin with. What caused their death: heparin or their underlying disease? All together now: comorbidities!

Heparin could be a defective product case, because the FDA has found one contaminant — oversulfated chondroitin sulfate — that may have been supplied as counterfeit heparin. Somebody paid for heparin, but instead got doctored dietary supplement that acts like heparin. And the FDA has said there may be other contaminants and there might be more than one source.

So who gets sued, who pays a verdict or settlement? Here’s where it starts to get complicated: heparin has one, big deep-pocket American defendant, but other companies apparently use its heparin. Deep Pockets got it from a supplier, who has a plant in China that works its magic with pig guts. A natural question is: who was the gatekeeper against counterfeit stuff, the supplier or Deep Pockets?

And where was the FDA? As some defense attorneys like to point out these days, the FDA determines if drugs are safe and effective. But the FDA said it inspected the wrong plant in China.

So, to recap the possible scenario, someone in China makes counterfeit heparin and they, or someone else, subs it in as real heparin, but the FDA inspected the wrong plant and the stuff gets through the suppliers and the manufacturer and to the patients. Talk about extended litigation and multiple defendants!

And have American product liability claims been tested against defendants in China? Nine months ago, the head of the Chinese FDA was accused of taking bribes in exchange for drug approvals and was executed. One of my colleagues said that might be more of an indication of how China values human life more so that how it values drug oversight. Already, China has waffled on the heparin issue: we’ll cooperate, but it wasn’t our fault; we’ll let the U.S. FDA set up show here, but stop criticizing us! American tort system, meet the concept of “saving face.”

And amidst this, the U.S. Supreme Court hasn’t yet ruled on preemption of drug liability claims. One common exception for preempted claims is manufacturing defect, which heparin could be. Or will the court rely on the FDA to determine if a product if defective before a plaintiff can sue?

Balance that against the fact that China is becoming America’s de facto industrial heartland and its prime lender and there may be a need to tread lightly.

Remember the old adage about opening up a can of worms? This litigation is more like a 55-gallon drum — of pig intestines.