WASHINGTON, DC (CBS) — New Jersey Senator Cory Booker is putting pressure on the nation’s banking industry, concerned that consumers may be having a service forced on them that they never approved.

Booker has written the CEO’s at 13 of the nation’s largest banks including Chase, Wells Fargo, PNC Bank, Bank of America and TD Bank.

He wants information on how they encourage customers to sign up for overdraft protection.

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The senator was not available to comment on his action, but in a press release pointed to a 2014 Pew study finding that more than half of those who overdrew their checking accounts and paid a fee could not recall ever consenting to that.

Federal law mandates a consumer “opt in” to such programs.

In the letters, copies of which accompanied the release, Booker says “I’m concerned that too many of our nation’s banks are increasingly driven to accumulate these fees, rather than pursue a business model that serves their communities, and are adopting certain practices to drive participation in so-called ‘overdraft protection’ practices.”

According to those letters, three of those national banks took in over $5 billion in such fees last year.