A group of US lawmakers wants to see cryptocurrency holdings declared at the nation's border – and advocates of the tech are pushing back.

Introduced last month, the Combating Money Laundering, Terrorist Financing and Counterfeiting Act of 2017 – which is actually the third iteration of a bill that debuted in 2011 – would bring a range of digital currency services under federal scrutiny, including those that provide transaction mixing services.

Yet, the provision that has attracted the particular ire of cryptocurrency advocates – especially those who prefer a regulation-light environment – is one that would make such holdings subject to disclosure requirements at US customs checkpoints. This means if a person trying to enter the country has more than $10,000 worth of bitcoin in their possession, under the proposed legal change, they would need to inform the relevant authorities.

Such requirements are already in place for payment methods like cash. But given the rising public profile of cryptocurrencies like bitcoin, coupled with the perception among policymakers that they could be used to fund terrorist activities, is driving legislative efforts like the bill currently under consideration.

[...] Thus far, the bill hasn't advanced significantly since being introduced last month, public records show. On 25th May, the measure was referred to the Senate Judiciary Committee for further consideration.

At press time, representatives for Senators Chuck Grassley and Diane Feinstein hadn't responded to CoinDesk requests for comment. The bill is also being sponsored by Senators John Cornyn and Sheldon Whitehouse, constituting a group of two Republicans and two Democrats.