On Wednesday, 37 state and district attorneys general filed a lawsuit against Alphabet Inc.'s Google, alleging that the company bought off competitors and used restrictive contracts to illegally preserve a monopoly for its Android app market.

The charges against Google's Play Store are the result of a nationwide investigation that began in September 2019 and has already resulted in three lawsuits against the firm. The lawsuits threaten to require significant changes in the way it makes billions of dollars in income across its various businesses, including advertising, in-app sales, and smart home devices.

The lawsuit, Google argued on Wednesday, is about bolstering a tiny group of prominent app developers who want special treatment, not about assisting small businesses or customers. It claims that, unlike Apple Inc.'s App Store on iPhones, Android supports Play Store competitors.

“Android and Google Play provide openness and choice that other platforms simply don’t,” the company said in a blog post.

The states, led by Utah, New York, North Carolina, and Tennessee, contend that Google has made “enormous profit margins” from the Play Store by using illegal practices to maintain monopolies in the sale of Android apps and in-app purchases.

According to the lawsuit, Google Play accounts for 90% of Android app downloads in the United States.