HARRISBURG, Pa (AP) — The American Civil Liberties Union said it will file the first-known legal challenge Tuesday

, the only northeastern state that doesn't allow it or civil unions.

The lawsuit, which will be filed in federal district court in Harrisburg, also will ask a federal judge to prevent state officials from stopping gay couples from getting married. It names Gov. Tom Corbett, Attorney General Kathleen Kane and three other government officials.

Among the plaintiffs are

one widow, nine other couples and one of the couples' two teenage daughters. The plaintiffs include four couples who were legally married in other states, but whose marriages go unrecognized by the state of Pennsylvania.

Stay tuned to PennLive for more on this developing story.

Lesbian spouses negotiate a world of double standards

Read the lawsuit and meet the plaintiffs

Pennsylvania would become the 14th state to legalize gay marriage if the lawsuit is successful. It also would force the state to recognize the legal marriages of all same-sex couples in other jurisdictions.

The plaintiffs, including Deb and Susan Whitewood, who have been together for 22 years, said their willingness to join the lawsuit was driven both by a desire to have the same legal and financial protections afforded to opposite-sex couples and the emotional satisfaction of seeking social justice.

"I wanted our relationship to be respected like everybody else's relationship," said Susan Whitewood, 49, who lives in the Pittsburgh suburb of Bridgeville. "That was first and foremost the reason for doing this. I wasn't looking for legal validation."

Her daughter, Abbey, 16, is also a plaintiff and said she is excited to fight for her family's values.

"I want to prove that young people like myself can change the world if they stand up for what they believe in," she said.

In the suit, the ACLU said that banning gay marriage satisfies no legitimate government or child welfare concerns of the state, since Pennsylvania judges routinely grant adoptions to same-sex couples that are viewed as in the best interest of the child.

"It serves only to disparage and injure lesbian and gay couples and their families," the lawsuit said.

For instance, the suit says, same-sex couples do not have access to a long list of legal and financial protections as do opposite-sex couples.