(CNN) -- The five-minute video opens with a man cruising along in his car, cracking open a bottle of what appears to be Beck's beer and taking a swig.
"We all know drinking and driving is against the law. You're not supposed to do that. But they didn't say anything about driving and then drinking," the man says to the camera. "You just have to be learned enough to understand the symbols of drunkenness."
The man, Richard Godbehere, posted the clip in February under the title "Let's Go Driving, Drinking!" to LiveLeak, a video-sharing site where users can vote on and donate to videos they like.
Even so, he appeared surprised when police showed up at his house in Kapa'a, Hawaii, to arrest him on charges of consuming alcohol while operating a vehicle and driving without a license.
"It's unbelievable," Godbehere told CNN. He says the video was meant as a parody. "There was no beer in that bottle." Godbehere is due in court in June, and police in Kaua'i told CNN the case will come down to whether a judge or jury believes him.
"Our traffic laws are in place for a reason, and Mr. Godbehere's blatant disregard for those laws is the type of behavior that won't be tolerated," said Kaua'i Police Chief Darryl Perry in a statement.
Social networks offer platforms for us to share everything on the Internet, from our relationship statuses to our political leanings and photos of our pets and children. But some people are discovering that what they share on Facebook, Twitter and other platforms constitutes evidence that can be used against them in a court of law.
One expert told CNN that anything posted online is material the government can use as evidence to arrest and charge a person.
"In criminal cases, almost all evidence is discoverable and police can obtain the evidence," said Bradley Shear, a Washington-area lawyer specializing in social media law. "It's just a matter of what hoops they have to jump through."
The government can subpoena deleted content from social media companies, as a judge did from Twitter for a case involving an Occupy New York protester in July 2012. But sometimes, law enforcement doesn't have to jump through any hoops to collect potentially incriminating evidence -- they just have to click around online.
"It's like that old saying," said professor Susan Rozelle, who teaches evidence and criminal law at Stetson University College of Law in Gulfport, Florida. "Don't put anything on your Facebook page you wouldn't tell your mother, or the local police department."
The most high-profile recent example of this was in Steubenville, Ohio, where social media played a role in the case of two football players who were found guilty last month of raping a drunken 16-year-old girl.
The girl didn't remember much of what happened when Trent Mays, 17, and Ma'lik Richmond, 16, sexually assaulted her at a party in August of 2012. Her family and law enforcement learned of the assault after cell phone pictures and videos, taken by partygoers, popped up on Facebook and other sites. One key piece of evidence was an Instagram photo of the two boys carrying the girl out of a house.
Mays, who shared photos of the girl naked and passed out, was also found guilty of disseminating a nude photo of a minor.
The case caught fire on both conventional media and social media after a crime blogger and former Steubenville resident, Alexandria Goddard, uncovered some of the photos, videos and messages posted online about the incident and accused the town of giving the boys preferential treatment because they played on the football team. Police denied the claim.
Just last month, two teenage girls were arrested and charged with intimidating a witness after police said they made threats against the victim on Twitter. Prosecutors have said they are considering additional charges against witnesses who refused to speak up. A grand jury will meet April 30 to hear evidence.
'... to whoever's vehicle i hit i am sorry'
Early on the morning of January 1 of this year, police in Astoria, Oregon, responded to a call about a hit-and-run on a residential street. There they found two cars had been sideswiped by an unknown driver, leaving behind a bumper cover and pieces of a taillight.
Later that day, an officer received a private Facebook message alerting her to a Facebook status update recently posted by Astoria resident Jacob Cox-Brown, 18. It read, "Drivin drunk... classsic ;) but to whoever's vehicle i hit i am sorry. :P"
Officers went to Cox-Brown's home and arrested him after finding a damaged vehicle missing pieces that matched those left behind at the crime scene.
In an interview with ABC affiliate KATU-TV, the owner of one of the damaged vehicles said what everyone watching the case was probably thinking: "Why would you post that? He basically just turned himself in."
Cox-Brown told KATU that his Facebook status update was "a big joke" and that he sideswiped the cars because of icy conditions. He is due in court April 22.
Shear, the social media law expert, said he would never allow a client to post anything like that online. But he argued that Cox-Brown's post alone would not be enough for a DUI conviction. Prosecutors would need additional evidence, such as a blood-alcohol-level report, he said.
"You want to focus on charging someone with something you can prove in the court of law," he said.
That may explain why police said Cox-Brown is charged not with driving under the influence but with two counts of "failing to perform the duties of a driver."
The Montreal Metro Drinking Marathon
A group of young partiers in Montreal gave authorities plenty of online evidence last month after a binge-drinking journey through the city's subways. The group participated in what they called the Montreal Metro Drinking Marathon, with plans to drink a beer at every station on the 30-stop Orange line.
They made it to 18 stations before losing focus, according to a post about it on Mook-life.com, a blog about youth culture in Montreal. "I guess alcohol got the best of us and we completely forgot what was going on at one point but in my opinion that makes us all winners!" said the March 25 post, which has since been taken down.
The group also posted photos, some with blurred faces, of members chugging beers on the trains and urinating at the subway stations -- both violations of city ordinances.
News sites republished some of the photos, and authorities took notice. Montreal police are now investigating the incidents and have asked for help in identifying the participants. A lawyer representing some of the partiers involved is negotiating with investigators, Montreal police said.
Canada and the United States have similar protections against suspects incriminating themselves while in custody, but voluntary gloating or confessions online are free game for law enforcement, legal experts said.
"What the Fifth Amendment protects against is compulsory confessions," Rozelle said. "No one compelled them to take photos of themselves drinking and peeing."
"The problem is that people don't realize that you can't take it back," added Shear. "It's almost impossible to unpost something."
When posting a photo is a crime
It's one thing to be arrested for posting a photo that shows you breaking the law. It's another to be arrested for posting a photo of someone else's handiwork.
In another case of social media consequences in Montreal, a woman was arrested earlier this month after she posted a photo on Instagram of graffiti she spotted on a city wall that depicted a high-ranking Montreal police officer with a bullet hole in his head. Jennifer Pawluck, 20, was accused of criminal harassment and intimidation, according to Montreal police.
"I think the person behind the artwork should be in my place ... all I did was take a photo," she told the Canadian Broadcasting Corporation.
Pawluck has not been formally charged but is scheduled to appear in court on May 24. A Montreal police spokesperson said there's more behind her arrest than just the posting of the photo, but declined to offer further details.
Legal experts say photos and videos, whether posted publicly online or obtained in a more discreet manner by the police, have to meet the same criteria: They must be authenticated, meaning the prosecutors must prove the images are what they seem and have not been altered or staged. And they can't be shown out of context.
"You can't just show a snippet that makes it seem worse than it is," said Rozelle, the Stetson University law professor.
When the accused admit to posting the materials themselves, authentication isn't as much of a question. But in the cases of Godbehere, in Hawaii, and Cox-Brown, in Oregon, the incriminating posts put them in the awkward position of having to disavow their own words, experts say.
Either way, Rozelle says, criminals' trumpeting their crimes is nothing new.
"People have always said foolish things," Rozelle said, "but now they have the ability to say it louder and to more people."