PUNCHES fly as gay marriage advocates and opponents clash outside Supreme Court while landmark case is heard inside

Gay marriage advocate Sergei Kostin punched opponent in the FACE



Police describe him as a 'professional activist' who was part of Occupy DC



Kostin rallied for Trayvon Martin, whose killer claimed he was attacked first



Now Kostin claims he was striking back after he took a punch to the gut



Midway through a National Organization protest in front of the US Supreme Court building, punches flew. One, which landed on the face of a marcher, was thrown by gay marriage advocate Sergei Kostin, a former Occupy DC member whom a source in the Washington, DC Metropolitan Police Department described as a 'professional activist.'



The other was a gut-punch that Kostin told MailOnline provoked him - one that no one else saw. If that punch flew, one observer countered, however, it's not clear how hard it could have been.



But if the swinging fists were half-imagined, the ideological confrontation on Tuesday was genuine. Both sides of the debate were out in force, with Christian opponents easily outnumbering advocates for gay marriage.



Inside, the Supreme Court heard oral arguments in a case that could determine whether the federal government or the 50 states will decide what a marriage is.

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Sergei Kostin (L) argues with a supporter of a traditional definition of marriage, outside the US Supreme Court. Moments later, Kostin punched him in the face. He claims the other man gut-punched him first

Kostin is a well-known gay rights activist in Washington, DC. His Facebook page shows him dressed in rainbow gear for several protests in the city. A source inside the DC Metropolitan Police Department told MailOnline that he is 'a professional activist'



Yahoo! News reported that the cast of characters included a drag queen in a rainbow tutu and devil horns, cross-carrying Christians who knelt in prayer, and a host of other activists.



The National Organization for Marriage (NOM) marchers 'were met by another small group of people that had stretched out a rainbow flag in front of them,' according to Yahoo.



'When they refused to budge from the street, NOM organizers urged everyone to just go around them. A NOM demonstrator began arguing with one of the men holding the flag, Sergei Kostin, and tried to push him out of the way.'

Enter the fisticuffs.



Neither the Metropolitan Police Department nor the National Park Police said they had any knowledge of the altercation, and no arrests were made.

Kostin took up the cause of the late Trayvon Martin in 2012. Martin, a black teen, was shot and killed by George Zimmerman, who said Martin attacked him first. Kostin himself is arguing the same about his confrontation in front of the Supreme Court, claiming that he was attacked before he threw a punch that landed on a man's face.

In a telephone interview with MailOnline, Kostin said he only threw an uppercut after he was attacked first, when he stepped between the anti-gay-marriage crowd and a lone sign-carrying woman, in an attempt to protect her.

'This gentleman had his hand on my chest,' Kostin said. 'I've been an activist for several years, and that kind of stuff doesn't bother me. But when he got closer to me, he threw a punch into my stomach.'



'In turn, when he did that I reacted back to him. That's when I clocked him.'



Kostin said no law enforcement officers intervened, and he hasn't heard from any since the confrontation.



He doesn't know the identity of the man he struck - only that he was 'twice my size.'

Kostin confirmed that he was a longtime member of the Occupy DC contingent that maintained an encampment in DC's McPherson Square for nearly nine months, ending in June 2012.

Kostin is a colorful character seen frequently at Washington, DC protests. In this photo, he demonstrated against the US government's use of drones in military operations. Kostin wore black lingerie and a pink sign reading 'CIA'

A woman carrying a 'Get Equal' sign and an American flag danced with a man dressed in heels to draw attention to the fight for gay marriage equality

He also protested the death of Trayvon Martin in 2012. Martin, a black teen, was shot and killed by George Zimmerman, who said Martin attacked him first.



Kostin himself is arguing the same about his confrontation in front of the Supreme Court, claiming that he was attacked before he threw his own punch.

Asked whether he would meet force with force again - and what would Gandhi do? - Kostin said he would think about it.



'When you get aggressive, then my passive resistance draws a line,' he explained. 'Passive resistance is passive, yes, but there's also that word "resistance" in there.'

