It's fair to say that until last week, no Super Bowl half-time show performer — let alone a Super Bowl viewer — ever considered the question of who owns the copyright on a backup dancer's costume. The performer? The costume-maker? The backup dancer? The NFL?

But that question marks the front line of copyright law this week, after Katy Perry's legal eagles dropped a cease and desist letter on a vendor selling a 3-D printed "left shark." Now the shark-making entrepreneur has fired back with a passionate letter of his own.

It's a blistering attack that casts doubt over whether Katy Perry even has standing to make the claim — based on Katy Perry's own words.

In case you swam under a rock last weekend, "left shark" was one of the dancers in Katy Perry's beach-themed number, "Teenage Dream," at Super Bowl XLIX. Viewers noted that the shark to Perry's left seemed rather less familiar with the routine than the shark to the right, becoming what might be uncharitably described as a hot mess of flailing fins, and an Internet meme was born.

A few days later, a Florida-based sculptor named Fernando Sosa entered the story. Sosa 3D-prints satirical, topical and occasionally NSFW items such as Governor Chris Christie wearing a traffic cone and carrying a sign that reads "traffic study," Senator Mitch McConnell as a turtle, and a butt plug that looks like Vladimir Putin.

Sosa decided to add a few left shark-themed figures to the mix — one regular left shark, one holding a beer bottle, a pink version, and a right shark for completists.

Then on Friday came the cease and desist.

Image: Fernando Sosa

Image: Fernando Sosa

Sosa says he was shocked. "If anything I expected more controversy regarding my previous works, which included homophobic world leaders and local politicians," he wrote in a blog post Monday. "I certainly didn't expect this reaction from a comical dancing shark."

But if there's anything we've learned in the last week, it's that one comical dancing shark can command the world's attention. Sosa said that he was ready to capitulate to the forces of Big Fish on Friday after reading the lawyers' letter — but changed his mind, and decided to "finally take a stand and break the usual cycle of rolling over or giving into legal threats." It probably helped that a New York University law professor had decided to represent him.

Sosa also posted a request for legal funds on GoFundMe, which met its modest $500 goal in 3 days.

Here's the letter Sosa's lawyer shot back — in which Perry is quoted at length. "I am no longer the boss," she said of her half-time show in an interview with Elle magazine. "I have to relinquish control." That statement gave Sosa's lawyer an opportunity to pounce.

The letter, full of savage burns, seems written as much for the wider Internet audience — many of whom are Perry fans — as for her legal representatives. Still, regardless of the outcome, we've got the makings of a case that copyright lawyers would love to sink their teeth into.