Abbott Labs (NYSE: ABT) got a ruling overturned yesterday that would have cost the company $1.8 billion, yet investors let shares slip down 1%. Either investors are completely blind, or they figure this fight is far from over.

I'm guessing the latter.

A court ruled in 2009 that Abbott's Humira infringed on patents owed by Johnson & Johnson (NYSE: JNJ) and ordered Abbott to pay damages, royalties, and interest to the tune of $1.8 billion.

Yesterday, an appeals court disagreed, throwing out the initial ruling. In fact, the panel of three judges actually invalided Johnson & Johnson's patents.

Humira is a big deal for Abbott, making up nearly a fifth of Abbott's revenue. Not having to worry about patent breaches should help the company get back to the task at hand: taking market share from Johnson & Johnson and Merck's (NYSE: MRK) Remicade and Amgen (Nasdaq: AMGN) and Pfizer's (NYSE: PFE) Enbrel.

But investors seem rightfully worried that the table could turn in the next round of appeals. Johnson & Johnson hasn't made a firm decision, but with a billion dollars at stake, the return on investment from paying the lawyers for a few more years seems like a foregone conclusion.

Unfortunately there isn't much Abbott's investors can do but wait and see what the next level of the court system decides. This is kind of like betting on a basketball team with a three point lead and two minutes on the clock. The team that's up has the advantage, but there's enough time left that things could easily change before the final buzzer sounds.

Keep track of Johnson & Johnson  and Abbott as they duke it out in court. Click on their names to add them to My Watchlist, which will help you keep track of all our Foolish analysis on the companies.

Johnson & Johnson and Pfizer are Motley Fool Inside Value picks. Johnson & Johnson is a Motley Fool Income Investor recommendation. Motley Fool Options has recommended a diagonal call position on Johnson & Johnson. The Fool owns shares of Johnson & Johnson. Motley Fool Alphaowns shares of Abbott Laboratories and Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool's disclosure policy is patently delicious.