New York is poised to become the latest US state to relax its laws covering marijuana. Governor Andrew Cuomo will make a surprise turnaround in policy later this week, to allow limited use of the drug for medical purposes.

As Colorado residents continue to flock to their local pot shops, after their state became from 1 January the first to allow the sale and possession of cannabis for recreational purposes, signs have emerged that New York will now make a small but important amendment to some of the strictest laws on the drug in the US. Cuomo is expected to announce an executive action in his annual state of the state address on 8 January, to permit a small number of hospitals to prescribe marijuana for medical use in the treatment of serious illnesses including cancer and glaucoma, the New York Times reported on Sunday.

Cuomo, a Democrat, has always been staunchly against legalising cannabis, including for medical use. Even though the likely announcement would only loosen restrictions on the drug very slightly, it will be seen as a significant move at a time when a number of states are liberalising their laws in ways ranging from the use of medical marijuana to decriminalising basic possession of the drug, up to full recreational use. Voters in Washington state have also voted to allow recreational marijuana and it is expected to follow Colorado later this year and become the second state to implement such laws.

More than 20 states currently have laws allowing a variety of medical uses of marijuana.

Cuomo is expected to emphasise that medical marijuana will only be allowed for a tightly circumscribed list of illnesses, to be drawn up by the state Department of Health.

By announcing a unilateral executive action, the governor will sidestep the legislative process in the state capital, Albany, where the senate has repeatedly struck down bills passed in the lower assembly to permit medical marijuana.

Ethan Nadelmann, the executive director of the Drug Policy Alliance, told the New York Times Cuomo’s move was “bold and innovative”.

Even limited medical marijuana use is banned under federal law but the Obama administration has signalled that it is not interested in actively pursuing prosecution in states that have relaxed their laws around the drug. Whether there will be any clash between federal law enforcement and state authorities in Colorado and Washington state remains to be seen.

In Colorado, the sale and use of recreational cannabis has so far produced no major problems beyond long lines of people waiting in the freezing cold outside dispensaries that successfully applied for licences to expand their business from filling medical prescriptions to making recreational sales.

California medical marijuana dispensaries fill prescriptions for patients with simple back ache or migraine headaches – some allow consumers to gather on the premises to smoke together or consume baked cannabis products.

New York will be a long way from such a permissive culture, but the smallest move in that direction from Cuomo represents a further liberal move from his administration. His speech on Wednesday is eagerly awaited, in the light of the election of the progressive liberal Bill de Blasio as the new mayor of New York City.

After winning plaudits for legalising same-sex marriage and moving to boost abortion rights and tighten gun control, Cuomo, who took office in 2011 and who has been talked about as a possible presidential contender in 2016, has been somewhat eclipsed in recent months by De Blasio. The New York mayor, who took office on 1 January, has dominated the political and media agenda with his pledge to address a “tale of two cities” by tackling his city's growing income gap.

This has chimed with developments in Washington DC, where President Barack Obama and congressional Democrats have signalled that they will make inequality a key theme in 2014.

Governor Cuomo’s expected about-face on marijuana use has been driven by his belief that a carefully crafted law can help seriously ill people in great need while limiting the potential for abuse, a source familiar with his plans told the New York Times. At the same time, Cuomo is up for re-election this year and one survey, conducted by the Siena College last May, found that 82% of state residents favour allowing marijuana for certain medical uses.

Conversely, New York City still has one of the nation’s most restrictive sets of cannabis laws. From 1973 to 2009, the state had one of the harshest penalty regimes for drug sale and possession in the country, enshrined in the now-notorious Rockefeller drug laws. These laws mandated a minimum of 15 years to life in prison for anyone convicted of selling as little as two ounces of heroin, cocaine or cannabis, or possessing four ounces of the same. The laws pushed the state prison population to a high of 75,000 inmates in 1999.

In 2009, then-governor David Paterson repealed the Rockefeller drug laws. The state prison population has been falling steadily since, with Cuomo announcing several prison closures since taking office and inmate numbers falling below 55,000.

Meanwhile, 11 January marks the 50th anniversary of the first time US federal authorities officially recognised a direct link between smoking tobacco and serious illness. In 1964 the US surgeon general, Luther Terry, released a report that concluded emphatically and unequivocally that smoking caused illness and death, and that the government should take action to curb it.