Rebellious, rambunctious, rocker, and rider are among the words Rock and Republic Jeans uses on its Web site to describe its CEO and head designer, Michael Ball.

In fact, the designer may be a bit too rebellious and rambunctious for his own good, according to a lawsuit filed yesterday in state Supreme Court by one of Mr. Ball’s former designers, Fred Naggar.

Mr. Naggar is accusing Mr. Ball of physically assaulting him at a popular Lower East Side restaurant last month. Mr. Nagger also claims that Mr. Ball violated their oral business contract.

Mr. Naggar worked for Rock and Republic as a consultant between 2003 and 2005, handling high-profile partners such as former musician Victoria Beckham and contributing to the company’s rapid growth, the suit says. The suit alleges that the business relationship soured by the end of 2005, when Mr. Naggar was forced to resign.

While both men were at a Lafayette Street restaurant, Butter, Mr. Ball smashed Mr. Nagger over the back with a glass, “showering Naggar with pieces of glass, ice, and liquid,” the suit alleges.

Mr. Nagger is demanding $1 million in back pay, plus 1% of Rock and Republic’s global gross sales and punitive damages. A spokeswoman at Rock and Republic did not return a call for comment.