WASHINGTON -- Supreme Court justices pushed back Monday against the idea of patenting human genes during oral arguments that ranged from baseball bats and chocolate chip cookies to imaginary plants in the Amazon.Amid a tangle of competing metaphors, conservative and liberal justices alike seemed to recoil at patenting isolated genes taken from the human body. Even if separated through clever technology, justices suggested, the genes remain a product of nature rather than an invention of man."Here, you're just snipping, and you don't have anything new," Chief Justice John Roberts Jr. told Gregory A. Castanias, an attorney for Myriad Genetics of Salt Lake City. "You have something that is a part of something that existed previous to your intervention."Liberal Justice Elena Kagan joined the conservative Roberts in offering examples that were critical of human-gene patenting. Repeatedly Kagan asked whether a company might patent a medically useful plant removed from its habitat deep in the Amazon.The question is telling, because the Supreme Court has declared that laws of nature and "natural phenomenon" may not be patented."Are you saying you could patent the plant because it takes a lot of ingenuity and a lot of effort to find it?" Kagan asked. The case is the first to confront the Supreme Court directly with the question of whether the human gene may be patented, although more than 4,000 such patents have been issued.Scientists with Myriad used mapping tools to identify genes associated with mutations that predispose patients to breast and ovarian cancers. Myriad obtained a number of patents relating to the isolated genes, enabling the company to control research and to charge for its genetics-based tests for breast cancer.The company, backed by others in the multibillion-dollar biotechnology and pharmaceutical industries, argues that the isolated gene can be distinguished from what's found in the body."A baseball bat doesn't exist until it's isolated from a tree," Castanias said Monday. "But that's still the product of human invention, to decide where to begin the bat and where to end the bat."Roberts, though, retorted that "you have to invent" a bat, whereas "you don't have to invent the particular segment of the [genetic] string. You just have to cut it off."