James Martin/CNET

The details of a bill that could ban some microtransactions in video games are now available, and the bill has bipartisan support. A Republican senator had announced his plans to introduce the "anti-loot box" legislation earlier in May.

Sen. Josh Hawley, a Republican from Missouri, filed legislation Thursday for his Protecting Children from Abusive Games Act, which would prohibit game developers from adding both loot boxes and pay-to-win microtransactions to a game targeted to those 18 years or younger, or games where the game makers know those under 18 are playing.

Supporting the bill are Sen. Ed Markey, a Democrat from Massachusetts, and Sen. Richard Blumenthal, a Democrat from Connecticut.

"Only the addiction economy could produce a business model that relies on placing a casino in the hands of every child in America with the goal of getting them desperately hooked," Sen. Hawley said on his website.

Stanley Pierre-Louis, CEO of the Entertainment Software Association (ESA), has criticized the legislation as being "flawed and riddled with inaccuracies" and promoted the raising of awareness around in-game spending tools rather than government involvement.

"It does not reflect how video games work nor how our industry strives to deliver innovative and compelling entertainment experiences to our audiences," Pierre-Louis said in an emailed statement. "The impact of this bill would be far-reaching and ultimately prove harmful to the player experience, not to mention the more than 220,000 Americans employed by the video game industry."

The bill, available on the senator's website, would make it unlawful for game publishers and distributors to include pay-to-win or loot box transactions in "minor-oriented games." That means games meant for those 18 years or younger, as well as games where the publisher and distributor have "constructive knowledge that any of its users are under the age of 18."

It defines a pay-to-win microtransaction as a transaction that makes users' progress in the game easier, gives them an award not available for those who don't pay, provides a competitive advantage or provides content that's otherwise no longer accessible because of a timer.

Loot boxes are considered an add-on transaction with randomized, or partially randomized, digital goods such as unlocking a feature, enhancing the entertainment value of a game or providing add-ons that're available only after the initial transaction.

Excluded in the draft legislation are microtransactions that increase the difficulty of a game, in-game cosmetics and other downloadable content that's neither pay-to-win nor a loot box.

Publishers and distributors that violate this legislation if it's passed would be subject to penalties by the Federal Trade Commission (FTC) and could be subject to civil action by state attorneys.

The bill also says that two years after its enactment, a study will be presented to Congress analyzing the psychological effects of pay-to-win microtransactions and loot boxes.

Because of the Memorial Day weekend, Congress will be in recess next week and will reconvene in June.

Originally published May 23, 1:17 p.m. PT.

Update, 1:32 p.m.: Adds quote from ESA and more background details from bill.