With the Supreme Court hearing arguments on Tuesday about the constitutionality of Proposition 8, the 2008 California ban on same-sex marriage, a number of recent polls show that a majority of Americans support legalizing it.

A CBS News poll released Tuesday showed that 53 percent of Americans say it should be legal for same-sex couples to marry, up from 46 percent in a New York Times/CBS News poll last July.

The poll found that a third of Americans who support legal marriages for same-sex couples said they did not always feel that way and had changed their thinking for a variety of reasons. Among those who changed their minds, one in five said that personally knowing someone who is gay or lesbian influenced them. Other reasons volunteered by respondents included increased tolerance (17 percent) or education (17 percent) and that support for same-sex marriage is the modern way of thinking about the issue (12 percent).

More Americans now report having a friend, family member or work colleague who is gay or lesbian, with 61 percent saying so, up from 44 percent in 2003. Among those with a close relationship to someone who is gay or lesbian, two-thirds support legalizing same-sex marriage; among those who do not know someone close who is gay or lesbian, 56 percent say gay marriage should not be legal.

Support for legalizing same-sex marriage is higher among Democrats (63 percent) and independents (56 percent) than Republicans (37 percent). Among younger Americans support is higher, with nearly three-quarters of those under 30 in support, compared with slightly more than half of those over 65 who say it should not be legal.

The CBS News poll was conducted by telephone from Wednesday through Sunday among 1,181 adults nationwide, with a margin of sampling error of plus or minus three percentage points.

A Pew Research Center report released last week described the increase in support for same-sex marriage over the last 10 years as among the largest shifts in American public opinion on any policy issue. In 2003, nearly 6 in 10 Americans opposed same-sex marriage, while about a third favored allowing gays and lesbians to marry legally. Pew’s recent survey found Americans have shifted substantially on the issue, with 49 percent supporting and 44 percent opposing same-sex marriage.

Other recent surveys have found similar trends, although variations in question wording produce slightly different levels of support among the polls. A CNN/ORC poll conducted March 15 to 17 found 53 percent of Americans said that marriages between gay and lesbian couples should be recognized by the law as valid, with the same rights as traditional marriages, and 44 percent said they should not – numbers that flipped from 2008, when 44 percent said the law should recognize these marriages as valid.

A poll conducted the first week of March by ABC News/Washington Post showed 58 percent of Americans saying same-sex marriage should be legal, and 36 percent saying it should be illegal. Support for same-sex marriage has steadily tracked upward in ABC/Post polls, from 37 percent in favor a decade ago, to a narrow majority supporting legalizing it in 2011.

A Fox News poll conducted March 17 to 19 showed 49 percent of voters in favor of legalizing same-sex marriage, up from 42 percent last year.

And a Gallup poll found that a slim majority of Americans said they would vote for a hypothetical law giving marriage benefits to gay federal government workers who are legally married. Fifty-four percent of Americans said they would vote for a law providing marriage benefits, including insurance, tax benefits and Social Security to same-sex partners of federal employees, while 39 percent said they would vote against such a law. The poll was conducted March 11 and 12.

All polls were conducted by live interviewers nationwide using landlines and cellphones, with margins of sampling error ranging between three and four percentage points.