A federal appeals court wrestled with those kinds of questions Thursday when it considered placing restrictions on patent protections for business practices. The case under review is being closely watched by financial services and software companies.

The number of patents on tax preparation strategies, investment techniques and other business methods has surged since 1998, when the Court of Appeals for the Federal Circuit opened the door to such claims.

That increase has led to widespread criticism that many of the patents, including one about how to teach golf lessons, are frivolous and spur excessive litigation.

The Federal Circuit said in February that it would reconsider its decade-old decision in a case that many patent experts say is one of the most important in years. Depending on how broadly the court rules, the case could make it harder for investment banks and software companies to patent their products.