Jamala representing Ukraine performs the song "1944" during the final dress rehearsal of the 2016 Eurovision Song Contest at Ericsson Globe Arena on May 13, 2016 in Stockholm, Sweden.

The European Broadcasting Union (EBU) -- the body that oversees the Eurovision Song Contest -- has strengthened its language against political posturing in a revised set of rules published at the end of July.

Previously the EBU banned lyrics and performances that bring the pan-European extravaganza "into disrepute." But a new clause goes further and forbids performers whose past may suggest a political agenda or break the law.

It says: "Neither the selected artist nor any member of the delegation shall have any antecedents likely to prompt the host country's national authorities to deny them access to the host country, in accordance with applicable national law."

In short: Don't send a singer with a past that will get her banned.

In the run-up to Eurovision 2017, which took place in the Ukrainian capital of Kiev in May, geopolitical foes Ukraine and Russia waged a propaganda war through the glitter-soaked contest.

The Russian broadcaster instigated the conflict by selecting Julia Samoylova -- a telegenic singer who had broken Ukrainian law by singing in the disputed territory of Crimea. Ukraine's security services swiftly banned her from entering the country, thereby violating the EBU's principle of inclusion. That Samoylova uses a wheelchair created a public relations nightmare for Kiev.

Russia's Eurovision broadcaster, claiming offense at the slight, withdrew from the contest and refused to air the program. Moscow's absence led Eurovision viewership to fall to 182 million -- down by 22 million from the year before.

The EBU sees the new clause as amplifying its earlier position on politics.

"There were similar formulations of this rule in earlier editions of the contest," says Dr. Frank-Dieter Freiling, the chairman of the Eurovision Song Contest Reference Group, which governs the event. "We have articulated it a bit more clearly and strongly to renew the message and to send a clear signal to everyone."

Earlier this summer, officials sent another signal: Ukraine's broadcaster was dealt a "substantial fine" -- up to 200,000 Euros, according to Ukrainian media. Russia's penalty for baiting Ukraine with its provocative choice of singer remains murky. "Russia has been called to order in a different way, but without making that public," Freiling says. "Both parties involved have been commented on."

The EBU's new language may well deter overt political wrangling. However, it's unlikely to dampen the on-stage political tension that makes Eurovision a hit with audiences from Australia to Azerbaijan. From pop music to television, culture inevitably reflects the world in which it's created -- warts and all.

"The definition of 'political' is still unclear and can be imposed very subjectively," says Dr. Dean Vuletic, a historian at the University of Vienna and a noted Eurovision scholar. "The new clause is open to interpretation."

He points out that plenty of recent acts have carried clear socio-political messages without irking the powers-that-be. Among them is Eurovision 2014 winner and bearded drag queen Conchita Wurst, who built a massive fan base ahead of the contest by railing against Vladimir Putin and Russia's anti-LGBT legislation. "Her song didn't carry political content, but she as a figure did," Vuletic says. "But Conchita embodied the sort of politics that people at the EBU like -- progressive, liberal, Western European."

Were the EBU to take a hard line on its own rules, the contest would lose much of its appeal, which stems partly from its anything-goes spirit. Thankfully the body's history of leniency suggests it will continue to tolerate acts that flirt with politics -- so long as they don't violate the laws of the host country.

Israel offers a colorful precedent, across time and topic. In 1983, Ofra Haza -- frequently dubbed "The Israeli Madonna" -- sang about the Jewish people's perseverance despite repeated attempts to destroy them. Her song carried extra weight since Eurovision took place in West Germany that year. Israel's 2007 song "Push the Button," which referenced nuclear war, was widely interpreted as a takedown of Iran's then-president Mahmoud Ahmadinejad. Singing to an accordion beat, the group sang: "The world is full of terror/ If someone makes an error/ He's gonna blow us up/ To biddy biddy kingdom come."

Officials can easily vet a song for political content and reach a conclusion. But a more unpredictable element remains the performers themselves. Artists carry secret passions and storied histories that frequently flow out during interviews and press conferences. At the most recent contest earlier this year in Kiev, Poland's Kasia Mos repeatedly drew attention to the plight of chained animals in her country. And Portugal's Salvador Sobral, the eventual winner, spoke up for refugees during his press conferences and wore an "S.O.S. Refugees" sweatshirt around the press center, which drew censure from the EBU.

Speaking to Billboard in a cramped room away from the spotlights at the contest, the Ukrainian rocker Yevhen Halych of the band O.Torvald issued a powerful statement of his own. "It's important to notice that I have a tattoo, made when weaponized conflicted started in our country," he said. "This dove of peace symbolizes my hope that in the nearest future, everything in my country will be OK."