About two months ago, the 27-year-old Microsoft engineer Pavel Yurevich was booking a flight on Southwest Airlines — something he often does — when he got an idea. Southwest does not charge so-called change fees, which means if you book a flight and then the price drops, you can re-book the flight for the lower price without penalty. This requires checking the fares constantly, however. There has to be a better way, Yurevich thought, in the stereotypical entrepreneur manner.

Yurevich called his former colleague, a coder named Chase Roberts who had experience building scrapers, or programs that pull data from websites. In college at Brigham Young University, Roberts built an app called Lunchbox that scraped the university’s events page for key phrases like “free pizza” to alert students to events with free food (one student called the app “nothing but incredible” in the campus newspaper).

Roberts loved the idea, but the pair wanted to see if there was a market for the service, for which they were hoping to charge customers $3 if the fare dropped by $10 or more. That’s when they learned they weren’t the first to have this idea.

In February 2016, Chris Lauinger, a quantitative researcher, created a tool called Dragon Fare Scanner that scraped Southwest fares and published them in close to real time, with the added benefit of alerting you if the price dropped on a flight you booked. Unlike other airlines, Southwest does not allow travel websites like Kayak and Expedia to publish its fares, so the travel blogosphere loved it. But within a few days of getting press, Lauinger received a cease-and-desist letter from Southwest. “Given legal concerns,” Lauinger wrote on his website, “the web app has been taken down.”

Dragon Fare Scanner wasn’t even the first automated service to face the ire of Southwest’s legal department. Around 2006 and 2007, a spate of automated check-in services including BoardFirst.com and LoveCheckIn.org popped up, guaranteeing users coveted first-come, first-served A-group boarding slots. Southwest sued both apps and forced them to discontinue service.

By the time Yurevich and Roberts learned about Southwest’s penchant for cease-and-desists, they were already committed to the idea. “Maybe they [Dragon Fare Scanner] just got really intimidated by Southwest,” Yurevich remembered thinking. “But we won’t.”

“To put it simply, you should stop.”

On November 6, a travel blog called Deals We Like posted about SWMonkey under the headline “Automatic Notifications when a Southwest Flight Drops in Price!” — an identical headline to the one almost two years prior about Dragon Fare Scanner. About 40 people signed up for the service, which convinced the pair the business was viable.

Two days later, they received a cease and desist email from Southwest, which stated that SWMonkey was “using Southwest’s proprietary and trademarked names and logos” and gave them seven days to fix it.

Yurevich and Roberts figured it was a bluff. Nowhere on their site did they use trademarked material, and the only direct reference to the airline was, they believed, under fair use (“save money on Southwest flights!”). Their images were all licensed via Creative Commons. Just to be safe, they photoshopped the company’s logo out of the tail fin of one of the images and added a disclaimer at the bottom stating “SWMonkey is not affiliated with Southwest Airlines or any of its partners in any way.”

Not good enough. Two days after that, they received another cease-and-desist from a different lawyer at Southwest. This one pertained not to intellectual property, but to Southwest.com’s terms and conditions which explicitly forbid using the information on Southwest.com “for or in connection with offering any third party product or service not authorized or approved by Southwest” or using any kind of automated crawler to access the site. It also made vague references to the Computer Fraud and Abuse Act (CFAA), the notorious anti-hacking law that has been widely panned as “the worst law in technology” due to its ridiculously broad reach. “To put it simply,” the letter summarized, “you should stop.”

The CFAA was supposed to be about preventing “malicious hacking” but is now deployed to prevent competition, said Charles Duan, director of the Patent Reform Project at Public Knowledge. In the case Power Ventures v. Facebook, the CFAA prevented users from gathering their own data and leaving Facebook’s platform. SWMonkey’s situation was similar, Duan said, because “by disallowing scraping of prices, Southwest makes it more difficult for travelers to compare prices against other airlines.”

On principle, Yurevich and Roberts believed they were in the right. “We, as consumers, don’t have the power to write our own terms and conditions and so we end up agreeing to whatever everyone throws at us,” Roberts said, without any ability to stipulate what companies do with our data. But after consulting with their lawyer, the two entrepreneurs came to the conclusion that they were, in the end, no different from the other startups. If they pressed on, Southwest would file suit in Dallas, and the cost of flying to Texas — Yurevich is in Washington and Roberts is in Utah — would be just the start of the expenses they would incur. Even if they managed to somehow pull off the long-odds victory in court and win the right to keep their business active, they still didn’t know for sure how profitable it would be.

Two weeks after launching, Yurevich and Roberts put up a blog post announcing the end of SWMonkey. “In the couple weeks that we were on-line, we were able to save customers more than 43,000 points and $550 dollars, and have made $45,” they wrote. “Because our $45 will not go very far in fighting litigation in federal court in Dallas, we have decided to save ourselves the headache and have shut down the service.”

That’s one last battle they are unwilling to concede, however. Southwest is now demanding the founders remove the site entirely even though it is now merely a landing page with a short and cheeky FAQ. “Southwest has no right to decide who can and can't publish information on the Internet,” they wrote in a blog post this week. On this front, at least, they stand a chance. “That’s pretty remarkable,” Duan said after reading the latest cease and desist. “Off the top of my head I can’t see any reason why they would be required to take down the site.”