Washington (CNN) Supreme Court justices appeared divided Tuesday during historic arguments over the constitutionality of gay marriage, with Justice Anthony Kennedy returning to a familiar role as the court's pivotal vote.

Chief Justice John Roberts -- who shocked conservatives with his swing vote to uphold Obamacare -- this time seemed to lean more closely to conservative justices.

The arguments unfurled inside a packed courtroom on Tuesday while supporters and opponents of same-sex marriage rallied outside -- with one protester even interrupting the arguments from within.

Lara Ramsey, left, and Jane Lohmann play with their 7-month-old son, Wyatt Ramsey-Lohmann. The two wed in 2004 after Massachusetts approved same-sex marriage. Massachusetts was the first state to do so.

Lara Ramsey, left, and Jane Lohmann play with their 7-month-old son, Wyatt Ramsey-Lohmann. The two wed in 2004 after Massachusetts approved same-sex marriage. Massachusetts was the first state to do so.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Michael Miller, left, and Ross Zachs marry on the West Hartford Town Hall steps after same-sex marriage became legal in Connecticut on November 12, 2008.

Michael Miller, left, and Ross Zachs marry on the West Hartford Town Hall steps after same-sex marriage became legal in Connecticut on November 12, 2008.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Amy Klein-Matheny, left, and her wife, Jennifer, exchange vows in Iowa after same-sex couples were allowed to marry there with an April 3, 2009, court ruling.

Amy Klein-Matheny, left, and her wife, Jennifer, exchange vows in Iowa after same-sex couples were allowed to marry there with an April 3, 2009, court ruling.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

In May 2009, Maine state Sen. Dennis Damon, left, hands Gov. John Baldacci the bill that the state Senate passed to affirm the right of same-sex couples to marry.

In May 2009, Maine state Sen. Dennis Damon, left, hands Gov. John Baldacci the bill that the state Senate passed to affirm the right of same-sex couples to marry.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Olin Burkhart, left, and Carl Burkhart kiss on the steps of the New Hampshire Capitol on January 1, 2010, after the state's law allowing same-sex marriage went into effect.

Olin Burkhart, left, and Carl Burkhart kiss on the steps of the New Hampshire Capitol on January 1, 2010, after the state's law allowing same-sex marriage went into effect.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

On August 21, 2010, TV reporter Roby Chavez, right, shares a moment with gay rights activist Frank Kameny during Chavez and Chris Roe's wedding ceremony in the nation's capital. Same-sex marriage became legal in Washington in March 2010.

On August 21, 2010, TV reporter Roby Chavez, right, shares a moment with gay rights activist Frank Kameny during Chavez and Chris Roe's wedding ceremony in the nation's capital. Same-sex marriage became legal in Washington in March 2010.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Phyllis Siegel, right, kisses her wife, Connie Kopelov, after exchanging vows at the Manhattan City Clerk's office on July 24, 2011, the first day New York's Marriage Equality Act went into effect.

Phyllis Siegel, right, kisses her wife, Connie Kopelov, after exchanging vows at the Manhattan City Clerk's office on July 24, 2011, the first day New York's Marriage Equality Act went into effect.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

On February 13, 2012, Washington Gov. Chris Gregoire celebrates after signing marriage-equality legislation into law. Voters there approved same-sex marriage in November 2012, defeating a challenge by opponents.

On February 13, 2012, Washington Gov. Chris Gregoire celebrates after signing marriage-equality legislation into law. Voters there approved same-sex marriage in November 2012, defeating a challenge by opponents.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

On March 1, 2012, Maryland Gov. Martin O'Malley, center, shakes hands with Senate President Thomas V. "Mike" Miller after signing a same-sex marriage bill. The law was challenged, but voters approved marriage equality in a November 2012 referendum.

On March 1, 2012, Maryland Gov. Martin O'Malley, center, shakes hands with Senate President Thomas V. "Mike" Miller after signing a same-sex marriage bill. The law was challenged, but voters approved marriage equality in a November 2012 referendum.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Jamous Lizotte, right, and Steven Jones pose for photos while waiting for a marriage license in Portland, Maine, on December 29, 2012.

Jamous Lizotte, right, and Steven Jones pose for photos while waiting for a marriage license in Portland, Maine, on December 29, 2012.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Rhode Island state Sen. Donna Nesselbush, right, embraces a supporter after the Marriage Equality Act was signed into law at the statehouse in Providence on May 2, 2013.

Rhode Island state Sen. Donna Nesselbush, right, embraces a supporter after the Marriage Equality Act was signed into law at the statehouse in Providence on May 2, 2013.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Delaware Gov. Jack Markell holds up legislation on May 7, 2013, allowing same-sex couples to wed in the state.

Delaware Gov. Jack Markell holds up legislation on May 7, 2013, allowing same-sex couples to wed in the state.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

At the state Capitol in St. Paul, Minnesota, Gov. Mark Dayton signs a bill legalizing same-sex marriage on May 14, 2013.

At the state Capitol in St. Paul, Minnesota, Gov. Mark Dayton signs a bill legalizing same-sex marriage on May 14, 2013.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

A couple celebrates at San Francisco City Hall upon hearing about the U.S. Supreme Court rulings on same-sex marriage on June 26, 2013. The high court cleared the way for same-sex couples in California to resume marrying after dismissing an appeal on Proposition 8 on jurisdictional grounds. The court also struck down a key part of the Defense of Marriage Act, a 1996 federal law defining marriage as between a man and a woman.

A couple celebrates at San Francisco City Hall upon hearing about the U.S. Supreme Court rulings on same-sex marriage on June 26, 2013. The high court cleared the way for same-sex couples in California to resume marrying after dismissing an appeal on Proposition 8 on jurisdictional grounds. The court also struck down a key part of the Defense of Marriage Act, a 1996 federal law defining marriage as between a man and a woman.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

On October 21, 2013, Cory Booker, right, officiates a wedding ceremony for Joseph Panessidi, center, and Orville Bell at the Newark, New Jersey, City Hall. The New Jersey Supreme Court denied the state's request to prevent same-sex marriages temporarily, clearing the way for same-sex couples to marry.

On October 21, 2013, Cory Booker, right, officiates a wedding ceremony for Joseph Panessidi, center, and Orville Bell at the Newark, New Jersey, City Hall. The New Jersey Supreme Court denied the state's request to prevent same-sex marriages temporarily, clearing the way for same-sex couples to marry.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Plaintiffs Laurie Wood, left, and Kody Partridge, center, walk with attorney Peggy Tomsic on December 4, 2013, after a judge heard arguments challenging Utah's same-sex marriage ban.

Plaintiffs Laurie Wood, left, and Kody Partridge, center, walk with attorney Peggy Tomsic on December 4, 2013, after a judge heard arguments challenging Utah's same-sex marriage ban.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Utah state Sen. Jim Dabakis, left, and Stephen Justesen acknowledge the crowd after being married in Salt Lake City in December 20, 2013.

Utah state Sen. Jim Dabakis, left, and Stephen Justesen acknowledge the crowd after being married in Salt Lake City in December 20, 2013.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

On November 13, 2013, Hawaii Gov. Neil Abercrombie, left, and former state Sen. Avery Chumbley celebrate with a copy of the Honolulu Star-Advertiser after Abercrombie signed a bill legalizing same-sex marriage in the state.

On November 13, 2013, Hawaii Gov. Neil Abercrombie, left, and former state Sen. Avery Chumbley celebrate with a copy of the Honolulu Star-Advertiser after Abercrombie signed a bill legalizing same-sex marriage in the state.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Same-sex couples get their marriage licenses at the Oakland County Courthouse in Pontiac, Michigan, on March 22, 2014, a day after a federal judge overturned Michigan's ban on same-sex marriage.

Same-sex couples get their marriage licenses at the Oakland County Courthouse in Pontiac, Michigan, on March 22, 2014, a day after a federal judge overturned Michigan's ban on same-sex marriage.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Jennifer Rambo, right, kisses her Kristin Seaton after their marriage ceremony in front of the Carroll County Courthouse in Eureka Springs, Arkansas, on May 10, 2014. Rambo and Seaton were the first same-sex couple to be granted a marriage license in Eureka Springs after a judge overturned Amendment 83, which banned same-sex marriage in Arkansas.

Jennifer Rambo, right, kisses her Kristin Seaton after their marriage ceremony in front of the Carroll County Courthouse in Eureka Springs, Arkansas, on May 10, 2014. Rambo and Seaton were the first same-sex couple to be granted a marriage license in Eureka Springs after a judge overturned Amendment 83, which banned same-sex marriage in Arkansas.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Julie Engbloom, left, and Laurie Brown embrace after marrying in Portland, Oregon, on May 19, 2014. A federal judge struck down the state's voter-approved ban on same-sex marriage.

Julie Engbloom, left, and Laurie Brown embrace after marrying in Portland, Oregon, on May 19, 2014. A federal judge struck down the state's voter-approved ban on same-sex marriage.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

William Roletter, left, and Paul Rowe get close after having their photo taken with their marriage certificate May 21, 2014, at Philadelphia City Hall.

William Roletter, left, and Paul Rowe get close after having their photo taken with their marriage certificate May 21, 2014, at Philadelphia City Hall.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Pastor Carol Hill from Epworth United Methodist Church speaks during a marriage-equality ceremony at the Kathy Osterman Beach in Chicago on June 1, 2014. The date marked the first day that all of Illinois' 102 counties could begin issuing marriage licenses to same-sex couples.

Pastor Carol Hill from Epworth United Methodist Church speaks during a marriage-equality ceremony at the Kathy Osterman Beach in Chicago on June 1, 2014. The date marked the first day that all of Illinois' 102 counties could begin issuing marriage licenses to same-sex couples.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Jennifer Melsop, left, and Erika Turner kiss after they were married in front of the Arlington County Courthouse in Arlington, Virginia, on October 6, 2014.

Jennifer Melsop, left, and Erika Turner kiss after they were married in front of the Arlington County Courthouse in Arlington, Virginia, on October 6, 2014.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Mary Bishop, second from left, and Sharon Baldwin, right, celebrate with family and friends following their wedding ceremony on the courthouse steps in Tulsa, Oklahoma, on October 6, 2014.

Mary Bishop, second from left, and Sharon Baldwin, right, celebrate with family and friends following their wedding ceremony on the courthouse steps in Tulsa, Oklahoma, on October 6, 2014.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Rob MacPherson, right, and his husband, Steven Stolen, hug during a news conference at the American Civil Liberties Union in Indianapolis on October 6, 2014.

Rob MacPherson, right, and his husband, Steven Stolen, hug during a news conference at the American Civil Liberties Union in Indianapolis on October 6, 2014.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Abbi Huber, left, and Talia Frolkis exit the City County Building in Madison, Wisconsin, after applying for a marriage license on October 6, 2014.

Abbi Huber, left, and Talia Frolkis exit the City County Building in Madison, Wisconsin, after applying for a marriage license on October 6, 2014.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

From left, plaintiffs Moudi Sbeity; his partner, Derek Kitchen; Kody Partridge; and Partridge's wife, Laurie Wood, celebrate after a news conference in Salt Lake City on October 6, 2014. The U.S. Supreme Court cleared the way for same-sex marriage in Utah when it declined to hear the state's appeal of a lower court ruling.

From left, plaintiffs Moudi Sbeity; his partner, Derek Kitchen; Kody Partridge; and Partridge's wife, Laurie Wood, celebrate after a news conference in Salt Lake City on October 6, 2014. The U.S. Supreme Court cleared the way for same-sex marriage in Utah when it declined to hear the state's appeal of a lower court ruling.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Joshua Gunter, right, and Bryan Shields attend a Las Vegas rally to celebrate an appeals court ruling that overturned Nevada's same-sex marriage ban on October 7, 2014.

Joshua Gunter, right, and Bryan Shields attend a Las Vegas rally to celebrate an appeals court ruling that overturned Nevada's same-sex marriage ban on October 7, 2014.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Chad Biggs, left, and Chris Creech say their wedding vows at the Wake County Courthouse in Raleigh, North Carolina, on October 10, 2014, after a federal judge ruled that same-sex marriage can begin in the state.

Chad Biggs, left, and Chris Creech say their wedding vows at the Wake County Courthouse in Raleigh, North Carolina, on October 10, 2014, after a federal judge ruled that same-sex marriage can begin in the state.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Newlyweds Jeff Delmay and Todd Delmay hug during a marriage ceremony in a Miami courtroom January 5, 2015. Florida began allowing same-sex marriages after a federal judge struck down the state's ban.

Newlyweds Jeff Delmay and Todd Delmay hug during a marriage ceremony in a Miami courtroom January 5, 2015. Florida began allowing same-sex marriages after a federal judge struck down the state's ban.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Shante Wolfe, left, and Tori Sisson become the first same-sex couple to file their marriage license in Montgomery, Alabama, on February 9, 2015. However, seven months after the U.S. Supreme Court ruling legalizing such nuptials nationwide, Alabama Chief Justice Roy Moore directed probate judges in his state to enforce the ban on same-sex marriage. Gay rights organizations swiftly denounced Moore's January 6, 2016, order.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Carlos McKnight of Washington waves a flag in support of same-sex marriage outside the U.S. Supreme Court on June 26, 2015. The Supreme Court ruled 5-4 that states cannot ban same-sex marriage, handing gay rights advocates their biggest victory yet. See photos from states that approved same-sex marriage before the nationwide ruling:

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Same-sex marriage in the U.S.

Photos: Same-sex marriage in the U.S.

Many questions on Tuesday centered around the definition of marriage and whether the decision to authorize or ban gay marriage should be left to voters in individual states or decided by the judicial system.

All eyes were on Justice Anthony Kennedy, considered a key vote for challengers to the state bans, who has penned three decisions in favor of gay rights over the years.

At the start of arguments he joined other conservatives concerned with the fact that marriage has been defined between a man and a woman for a long time. "This definition has been with us for millennia," he said. "And it's very difficult for the court to say: 'Oh, well, we know better.' "

But later Kennedy pressed John Bursch, a lawyer defending the bans: "Same sex couples say: 'Of course, we understand the nobility and the sacredness of the marriage. We know we can't procreate, but we want the other attributes of it in order to show that we, too, have a dignity that can be fulfilled.' "

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Kennedy also said that Bursch's assertion "that only opposite-sex couples can have a bonding with the child" was "just a wrong premise." When Bursch said the rate of out-of-wedlock birth has gone up in the country, Kennedy noted that if Bursch were to prevail, it might be difficult for same-sex couples to "adopt some of these children."

"I think," Kennedy said, "the argument cuts quite against you."

He also brought up the fact that marriage "bestows dignity." "These parties say they want to have that same ennoblement," he said.

Chief Justice John Roberts was also concerned with the traditional definition of marriage. He said this to Mary L. Bonauto, an attorney representing the challengers: "You're not seeking to join the institution, you're seeking to change what the institution is."

He expressed concern about closing off the debate currently going on in the states. "I mean, closing of debate can close minds, and it will have a consequence on how this new institution is accepted."

"People feel very differently about something if they have a chance to vote on it, than if it's imposed on them by the courts," he said.

Conservative Justice Antonin Scalia and Justice Samuel Alito were sharply critical in their questioning of Bonauto.

Scalia said that the issue is not whether there should be same-sex marriage, "but who should decide the point."

Alito brought up how long marriage has been considered between a man and a woman and cast doubt that such a definition was meant to demean same-sex couples.

Justice Sonia Sotomayor and other liberals seemed supportive of the challengers. When Bursch said that the issue should not be decided by the courts, Sotomayor pushed back. "I suspect even with us giving gays rights to marry that there's some gay people who will choose not to. ... Just as there are some heterosexual couples who choose not to marry. So we're not taking anybody's liberty away."

Steve Vladeck, a constitutional law professor at American University and CNN analyst, said Tuesday's session revealed few surprises to close observers of the court who expected Kennedy and Roberts would be the swing votes on this case.

Photos: The many signs of #SCOTUS Photos: The many signs of #SCOTUS Outside the Supreme Court of the United States, people hold signs calling for "equal justice under law." Hide Caption 1 of 14 Photos: The many signs of #SCOTUS A group against same-sex marriage prays in an "appeal to heaven" outside the Supreme Court. Hide Caption 2 of 14 Photos: The many signs of #SCOTUS Catherine Quinn of Detroit holds up her sign supporting same-sex marriage outside the Supreme Court. Hide Caption 3 of 14 Photos: The many signs of #SCOTUS Pastor Larry Hickam holds a sign of what he says is the definition of marriage outside the Supreme Court. Hide Caption 4 of 14 Photos: The many signs of #SCOTUS Kevin Rosseel of Washington stands outside the Supreme Court with his sign in support of same-sex marriage. Hide Caption 5 of 14 Photos: The many signs of #SCOTUS Stephanie Jones and Diana Iwanski of Clermont, Florida, share their sign in support of same-sex marriage outside the Supreme Court. Hide Caption 6 of 14 Photos: The many signs of #SCOTUS Sarah Rauber of Maryland stands in front of the Supreme Court. Hide Caption 7 of 14 Photos: The many signs of #SCOTUS McKenna Inskeep hands out stickers in support of marriage equality outside the Supreme Court. Hide Caption 8 of 14 Photos: The many signs of #SCOTUS Mike May of Cleveland argues against same-sex marriage in a debate outside the Supreme Court. Hide Caption 9 of 14 Photos: The many signs of #SCOTUS Outside the Supreme Court, John Lewis and Stuart Gaffney of San Francisco hold signs celebrating their marriage. Hide Caption 10 of 14 Photos: The many signs of #SCOTUS Senior Novice Sister Sedusa Poly Tishun shows off her face paint outside the Supreme Court. "We're here raising up our voices and our glitter in shouts of joy in support of marriage equality," Tishun said. Hide Caption 11 of 14 Photos: The many signs of #SCOTUS Andrew Damron of Brooklyn, New York, holds up a sign with the motto "You Only Live Once" in support of same-sex marriage. Hide Caption 12 of 14 Photos: The many signs of #SCOTUS Andrew Zibell of Brooklyn, New York, holds a sign in front of the Supreme Court that shows his support of same-sex marriage. Hide Caption 13 of 14 Photos: The many signs of #SCOTUS Senior Novice Sisters Ray Deeo Active and Allie Lewya show off their face paint in support of same-sex marriage. Hide Caption 14 of 14

"We heard both of them in the arguments today showing support for both sides of the argument, showing skepticism for both sides of the argument," Vladeck said. "I think the headline here is it's about what we expected. It's going to be close, it's going to be divisive and it's going to come down to Kennedy and Roberts."

Vladeck also cautioned against reading too much into the justices' questioning and comments during the oral arguments, which account for just a few hours in the multi-month process of deciding such an consequential case.

The emotion of the case also flooded into the courtroom, as one protester seated inside began shouted and screaming in the middle of the arguments.

"If you support gay marriage you will burn in hell," the protester shouted before police quickly detained the man and dragged him out of the courtroom while he continued to scream.

"Rather refreshing actually," conservative Justice Antonin Scalia quipped as the man was dragged out to laughter in the courtroom.

Lawyers with the pro-gay marriage organization Lambda Legal, which represented two of the cases wrapped into the Supreme Court case "an awe-inspiring and singular moment in the march towards justice."

"It was incredibly moving to gather in the Supreme Court chamber with their parents and all 30 plaintiffs in these historic cases. Mary and Doug were fantastic, making a compelling and to my mind irrefutable case on their behalf," Lambda Legal's Alphonse Gerhardstein said of the lawyers who argued in favor of same-sex marriage before the court on Tuesday.

U.S. Solicitor General Donald Verrilli, who represented the Obama administration's views, also presented arguments in favor of same-sex marriage, focusing on equal protection under the 14th amendment and likening bans on same-sex marriage to handing second-class status to gay Americans.

"I don't know why we would repeat history," he said.