Jan. 18, 2010 -- Eight in 10 Americans support legalizing marijuana for medical use and nearly half favor decriminalizing the drug more generally, both far higher than a decade ago.

With New Jersey this week poised to become the 14th state to legalize medical marijuana, 81 percent in this national ABC News/Washington Post poll support the idea, up from an already substantial 69 percent in 1997. Indeed the main complaint is with restrictions on access, as in the New Jersey law.

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Fifty-six percent say that if it's allowed, doctors should be able to prescribe medical marijuana to anyone they think it can help. New Jersey's measure, which is more restrictive than most, limits prescriptions to people with severe illnesses. State health officials can add to the list.

DECRIMINALIZE? – Apart from medical marijuana, there have been recent efforts to decriminalize marijuana more broadly in some states. A preliminary vote on one such measure is to be held in the Washington state Legislature this week. In California organizers say they've collected enough signatures to hold a statewide referendum on the issue next fall. And a separate proposal in California to legalize and tax the drug cleared a legislative committee last week. A Field poll there in April found 56 percent support for the idea, which its backers say would raise $1.3 billion a year.

Nationally, this survey finds 46 percent support for legalizing small amounts of marijuana for personal use – the same as it was last spring, and well above its level in past years, for example 39 percent in 2002 and 22 percent in 1997.

GROUPS – Age is a factor. Just 23 percent of senior citizens favor legalizing marijuana for personal use; that jumps to 51 percent of adults under age 65. There are political and ideological differences as well: Thirty percent of conservatives and 32 percent of Republicans favor legalization, compared with 49 percent of independents, 53 percent of Democrats and more than half of moderates and liberals alike (53 and 63 percent, respectively).

Medical marijuana, for its part, receives majority support across the political and ideological spectrum, from 68 percent of conservatives and 72 percent of Republicans as well as 85 percent of Democrats and independents and about nine in 10 liberals and moderates. Support slips to 69 percent among seniors, vs. 83 percent among all adults under age 65.

There are similar divisions on whether medical marijuana should be restricted or made available to anyone a doctor thinks it would help. Overall, 56 percent, as noted, prefer no restrictions, while 21 percent say it should be limited to terminally ill patients and an additional 21 percent say it should be limited to those with serious but not necessarily terminal illnesses.

Liberals are 23 points more apt than conservatives, and Democrats 20 points more likely than Republicans, to oppose restrictions. There's also a difference between the sexes, with men 10 points more likely than women to say the doctor should decide.

But the main difference is whether people think marijuana should be permitted for medical uses in the first place. Among supporters, 63 percent would rely on the doctor's discretion. Among those who oppose medical marijuana, 75 percent say that if it is allowed, it should be limited to seriously or terminally ill patients.

New Jersey passed its medical marijuana law this month and outgoing Gov. Jon Corzine is expected to sign it tomorrow morning, his last day in office. Medical marijuana first became legal in California in 1996, followed by Alaska, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Mexico, Oregon, Rhode Island, Vermont and Washington state.

METHODOLOGY – This ABC News/Washington Post poll was conducted by telephone Jan. 12-15, 2010, among a random national sample of 1,083 adults, including landline and cell-phone-only respondents, with an oversample of African Americans (weighted to their correct share of the population) for a total of 153 black respondents. Results for the full sample have a 3.5-point error margin. Click here for a detailed description of sampling error. Sampling, data collection and tabulation by TNS of Horsham, PA.