Law profs Kal Raustiala and Chris Sprigman make the case for copying:

The conventional wisdom today is that copying is bad for creativity. If we allow people to copy new inventions, the thinking goes, no one will create them in the first place. Copycats do none of the work of developing new ideas but capture much of the benefit. That is the reason behind patents and copyrights: Copying destroys the incentive to innovate.

Except when it doesn't. There are many creative industries...that lack protection against copying (or did for a long time). A closer look at these fields shows that plenty of innovation takes place even when others are free to copy. There are many examples of successful industries that survive despite extensive copying. In fact, some even thrive because they are so open to copying.

Their examples include cuisine, finance, fashion, and football. Here's what they have to say about the latter:

With myriad possibilities for formations and plays, football strategy is always changing—but none of it is protected against copycats. This hardly discourages great coaches from innovating. Exhibit No. 1 is the West Coast Offense, which relies on quick, short passes to control the ball and gain incremental yardage. The idea was the brainchild of Bill Walsh, who in the 1960s coached the Cincinnati Bengals [*], then a recently formed and hapless NFL expansion team. Cincinnati, he said, "was probably the worst-stocked franchise in the history of the NFL. So in putting the team together, I personally was trying to find a way we could compete."

His way was to develop a new style of offense. Later, when he was coach of the 49ers, Mr. Walsh's ideas helped to lead the team to three Super Bowl wins. Traditionalists at first dismissed his offense as a gimmick. But no one could dispute its success. Eventually, it was imitated by the Green Bay Packers, the Philadelphia Eagles and many other teams....

[I]n sports there are practical barriers to immediately copying a successful new tactic. The first time a play, formation or strategy is used, it can create a big element of surprise. After that, opponents can reverse engineer the idea relatively quickly. More difficult is the process of rebuilding a team to take full advantage of the innovation. This takes time. Economists refer to this window as the first-mover advantage.

Bonus reading: Douglas Clement on "Creation Myths."

[* Down in the comments, Warty points out that Walsh was the Bengals' offensive coordinator, not the head coach.]