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Intellectual Ventures (IV) is seeking a major new investment to expand its controversial patent trolling operations but, unlike on past occasions, Apple(s aapl) is not coming along for the ride.

According to a Reuters report, Apple has turned down an invitation to join Microsoft(s msft) and Sony in backing a new IV patent acquisition fund that could be used as a vehicle to extract licensing fees and file lawsuits against companies.

The news comes at a time that Congress is working on a law, the Innovation Act, intended to curb abuse of the patent system through measures like fee shifting and new legal discovery rules that would make it harder for patent trolls to swamp their targets with litigation costs.

The rise of patent trolls, which are a target of the proposed law, can be traced in no small part to Intellectual Ventures, which has armed thousands of shell companies with old patents in recent years. While Apple invested in earlier IV funds, its reluctance to do so again may stem from the fact that it is being swamped by trolls itself; in February, the company complained that it has had to go to court with trolls 92 times in the last three years.

“Microsoft and Sony’s investments give IV a fresh war chest to buy new patents,” a patent analyst told Reuters in relation to the new IV fund.

Earlier this year, Intellectual Ventures launched a Political Action Committee to lobby for patent trolls in Washington, a development that is likely galling for the companies who have had to pay off IV, and now must watch it use some of their money to seek protection from Congress to continue its trolling operations.