HARTFORD, Conn. — The Connecticut State Supreme Court ruled today the government cannot deny equal marriage rights to same-sex couples, on the basis of equal protection clauses in the state’s constitution. The court ruled 4-3 to overturn the state’s statutory same-sex marriage ban.

Writing for the majority, Justice Richard N. Palmer said the court found that “segregation of heterosexual and homosexual couples into separate institutions constitutes a cognizable harm,” due to “the history of pernicious discrimination faced by gay men and lesbians, and because the institution of marriage carries with it a status and significance that the newly created classification of civil unions does not embody.”

The majority opinion continued, “Interpreting our state constitutional provisions in accordance with firmly established equal-protection principles leads inevitably to the conclusion that gay persons are entitled to marry the otherwise qualified same-sex partner of their choice. To decide otherwise would require us to apply one set of constitutional principles to gay persons and another to all others.”

According to the Williams Institute, the U.S. Census Bureau’s 2007 American Community Survey found that there are more than 9,500 same-sex couples living in Connecticut. A majority, 53 percent, are female. Nearly a third of same-sex couples in the state are raising an estimated 5,700 children. The survey also found that the media household income of Connecticut same-sex couples with children is $69,500 — 30 percent below the median income for opposite-sex couples with children ($100,900). As of early 2008, more than 1,850 same-sex Connecticut couples — or about 20 percent of the total number of same-sex couples in the state — had entered into a civil union.

The ruling does not take place immediately, but will become law on Oct. 28. The first marriages will be able to take place sometime in early November. Connecticut is the third state to legalize marriage between same-sex couples. Massachusetts legalized marriage in 2004 and California in May 2008.

Simon Aronoff and Cathy Renna contributed to this report.