By Tom Hals and Hyunjoo Jin

(Reuters) -The judge overseeing Twitter Inc's $44 billion lawsuit against Elon Musk has a no-nonsense reputation as well as the distinction of being one of the few jurists who has ever ordered a reluctant buyer to close a U.S. corporate merger.

Kathaleen McCormick took over the role of chancellor or chief judge of the Court of Chancery last year, the first woman in that role. On Wednesday, she was assigned the Twitter lawsuit which seeks to force Musk to complete his deal for the social media platform, which promises to be one of the biggest legal showdowns in years.

"She already has a track record of not putting up with some of the worst behavior that we see in these areas when people want to get out of deals," said Adam Badawi, a law professor who specializes in corporate governance at the University of California Berkeley. "She is a serious, no-nonsense judge."

In contrast to Musk's brash and volatile behavior, she is known as soft-spoken, approachable and amiable -- but a person who also stands her ground. She advocates respect among litigants and integrity at legal conferences.

"We've always had each other's backs, we've always gone out for drinks after arguments and maintained this level of civility," she told a gathering at the University of Delaware this year.

After weeks of confrontational tweets suggesting Twitter was hiding the true number of fake accounts, Musk said on July 8 he was terminating the $54.20-per-Twitter share acquisition, worth $44 billion. On Tuesday, the social media platform sued.

McCormick on Friday scheduled the first hearing for July 19 in Wilmington, when she will consider Twitter's request to expedite the case and conduct a four-day trial in September.

Shares of Twitter were up about 2% to $37.11 in midday trading on Friday, but still more than 30% below the deal price.

Judges have ordered reluctant buyers to close corporate acquisitions only a handful of times, according to legal experts and court records. One of those was McCormick.