It may go down as the most expensive water-balloon fight in history.

On Tuesday, a Texas jury began hearing arguments in a dispute between the inventor of Bunch O Balloons, a toy used to fill dozens of water balloons at once, and TeleBrands Corp., the company known for the “As Seen on TV” logo, which makes a similar product.

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For small businesses, the costs of a patent dispute can be more than just financial. Even if a company wins, “they might lose some momentum that they will never get back,” said Mark Lemley, a Stanford Law School professor.