SAN FRANCISCO (KCBS)— San Francisco’s new law legalizing home shares suffered a setback Monday when HomeAway filed a lawsuit challenging the measure.

HomeAway, a vacation rental marketplace, claimed the law unfairly benefits Airbnb while making it difficult for other home- share platforms to do business.

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The lawsuit claims the legislation, by supervisor David Chiu, was crafted in a way that legalized Airbnb home shares while preventing companies like theirs from doing business in San Francisco.

Micahel Simons, an attorney for HomeAway called the legislation discriminatory.

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“We see how the law is written and when you take it at face value, it’s discriminatory and unconstitutional and we plan to challenge it,” Simons said.

Meanwhile, opponents of home shares like San Francisco activist Dale Carlson, welcome the lawsuit as a way to shed light on what the new law actually does.

“It’s only after a very careful, very thorough reading of the legislation that actually passed the board [of supervisors, people realized; holy smokes. Not only did Chiu give theses guys a break on their back taxes, he gave them a monopoly,” Carlson.

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Carlson and other home share opponents say legalizing home shares will hurt affordable housing and damage residential neighborhoods by allowing anyone’s home to become a hotel and they’re planning a ballot measure next year to challenge the law.