In the new lawsuit filed Thursday in U.S. District Court in St. Louis, Morley alleges he alone invented the Square card reader and the magnetic stripe decoding algorithms on Square’s app.

“He created what became the Square reader; that was Professor Morley’s technical contribution,” said Morley’s attorney, Brad Caldwell. “He also contributed a lot to the business side, helping them understand the way credit cards are processed.”

Square Inc. has grown to a valuation of $5 billion as a result of Morley’s contributions, his lawsuit alleges.

“Mr. Dorsey and Mr. McKelvey conspired with the objective of owning the lion’s share of the company and excluding Dr. Morley from receiving his share as a co-founder,” the lawsuit alleges.

Square plans to vigorously fight the lawsuit, according to spokesman Aaron Zamost.

“It’s not surprising that Morley would file another desperate, baseless patent lawsuit given how poorly his initial claims have been received by the patent authorities,” Zamost wrote in an email to the Post-Dispatch, referring to counterclaims Morley made in the 2010 case.