In a year of soaring cryptocurrency prices and countless initial coin offerings, it's perhaps unsurprising that, over the course of 2017, regulators worldwide stepped in to define how they would oversee what had been to date a legally murky environment.

From China's crackdown on exchanges to the SEC's report on The DAO, 2017 was perhaps one of the most significant years to date on the regulatory front. Indeed, the year saw regulators from many of the world's leading economies issue investor alerts and cautionary statements about financial use cases for the tech.

The past two months especially have seen growing activity on the ICO funding model, as seen by bans in major Asian countries to enforcement actions in North America.

In this article, we look at some of the big policy shifts from the past 12 months – many of which may have set the stage for further industry-defining developments in the year ahead.

It was the first week of 2017 and China's "Big Three" bitcoin exchanges – OKCoin, Huobi and BTCC – were being warned by the country's central bank.

That warning about staying compliant with "relevant laws and regulations" was followed in February by a freeze on withdrawals and the creation of new trading fees – both of which were measures imposed by the People's Bank of China in a stated effort to curb the risk of money laundering. And after months of waiting, exchanges ultimately returned access to funds to users in late May.

Officials in the world's most populous nation ultimately ordered those cryptocurrency exchanges to cease trading and shut down in mid-September, which combined with BTCC's closure effectively ended the "Big Three" ecosystem and pushed trading activities within China to over-the-counter markets.

News of the pending shutdowns came just days after the country stopped ICOs within its borders, saying the campaigns operated by "illegally selling and distributing tokens."

Where 2018 will head remains to be seen, though commentators on state-owned television in China have said in recent months that OTC cryptocurrency trading may be deemed against the law as well.

Rumors had circulated for months that the SEC would move to define how it would regulate ICOs. Yet the agency played its cards close until late July, when it declared that U.S. securities laws could be applied to some token sales depending on the nature of the token itself and the manner in which it was offered.

The funding model, through which the sale and distribution of cryptographic tokens would be used to kickstart work on a new blockchain network, was at the heart of The DAO, the now-defunct funding vehicle that raised millions of dollars in ethers in 2016 through the sale of DAO tokens. It collapsed later that summer following a debilitating exploit, sparking months of infighting, recovery efforts and, ultimately, a split in the ethereum blockchain.

According to a report published by the SEC in July, the DAO tokens were securities under U.S. law, though the agency said that it had declined to pursue any enforcement action related to the sale.

The SEC wrote at the time:

The agency's statements are significant because they sparked a host of similar warnings and publications from other regulators around the world.

The SEC itself would go on to warn about celebrity endorsed ICOs and public-stock scams that use the funding model as a way to entice investors. The agency has also pursued civil lawsuits against ICO organizers since July through a newly-created unit focused on digital investigations.

CoinDesk readers are likely familiar with the long-running saga of cryptocurrency regulation in Russia.

And while recent statements from senior lawmakers suggest that Russia's State Duma may finally approve rules governing the trade and issuance of cryptocurrencies, statements from earlier this year from president Vladimir Putin are arguably more impactful for the tech's future in the country.

In late October

, the Kremlin published five orders from Putin focused on various uses for the tech. He ordered new registration requirements for cryptocurrency miners, the application of securities laws to the initial coin offering (ICO) funding model and research into how the tech could be used as part of a digital payments ecosystem in the Eurasian Economic Union.

Echoing moves by other countries in the past year, Putin also ordered the creation of a regulatory "sandbox" for companies that use technologies like blockchain to develop new products and services.

While the orders undoubtedly nudged forward the work on legislation around cryptocurrencies, Putin's edicts have arguably advanced efforts to integrate the tech into the Russian state government infrastructure. They also came months after the Russian leader briefly met with ethereum creator Vitalik Buterin.

Other leaders in Russia have pushed the idea of using blockchain for public-sector purposes as well. Prime minister Dmitry Medvedev, for example, ordered government officials to begin researching uses of blockchain last spring.

Disclosure: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in BTCC.

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