Liu’s visit did not herald a breakthrough in trade talks, nor did it end well for Bai, who ended up spending the Lunar New Year in a police cell. He is now free on bail and facing charges that include assaulting a security officer, who sustained a knee injury during efforts to restrain him.

As well as casting a brief shadow over the high-level trade talks, the episode has shone a light on the desperate lengths to which dissidents who have fled China will go to make their voices heard, despite the slim chance of success and, in the case of Bai, the legal peril such protests may herald.

Like many Chinese activists who continue to protest from overseas, Bai’s first foray into confronting the authorities was through the country’s “petitioning” system, a process by which aggrieved citizens can file complaints – often pertaining to local government – to higher-level officials in the hope of intervention.

The system is notoriously opaque, with requests often going unanswered or, worse, met with harsh pushback from local governments, who have been known to enlist “petition blocking” companies to intercept petitioners and forcibly return them to their place of origin.

Bai, who now works odd jobs in Flushing, Queens, said he petitioned the government – by written correspondence and in person – more than 100 times, calling on officials to intervene in what he said was harassment and surveillance at the hands of Shanghai authorities. The Shanghai Public Security Bureau did not respond to a request for comment.

Elderly woman exonerated after being jailed for petitioning over land dispute

A handful of receipts he showed the South China Morning Post show that government bodies such as the State Bureau for Letters and Calls in Beijing and the Ministry of Public Security did receive his complaints.

He said he was never given an official written response, and alleged that Shanghai authorities forbade him from travelling to Beijing during the highly sensitive legislative sessions in March 2016.

In response, the petitions bureau on Friday said Bai would have to visit the bureau in person to check if his letters had been received or processed.

But Bai’s latest attempt to win the attention of Chinese authorities may prove to be his costliest.

Video shot by fellow protesters on the afternoon of January 30 shows Bai being restrained by Secret Service officers as soon as he ducked under a security perimeter, then falling to the ground as Liu's motorcade drove past.

As Bai was forced to the ground, he appeared to land on the leg of a Secret Service officer, who, according to federal prosecutor John Cummings, ruptured a tendon in his knee. His cry of “I’m hurt bad” can be heard in the video.

Addressing the court last week as Bai – solemn-faced and dressed in orange prison garb – listened via an interpreter, Cummings acknowledged that there was no evidence of “vicious probable cause” in Bai’s actions, but argued that his “wilful” disregard of law enforcement efforts, among other factors, warranted a sentence of up to 87 months.

Such a prison term would be a far cry from the six hours of community service Bai was sentenced to in 2016 when he blocked the motorcade of Chinese Premier Li Keqiang in New York, before being restrained by police officers.

Bai, who last week pleaded not guilty, was not fazed by the possibility of a harsh sentence.

“Seventy to 80 months? Even if it were 70 to 80 years I still wouldn’t plead guilty,” he said the morning after being released on bail. Bai made the remarks while staying with a friend in Washington before leaving for his home in New York, where he must adhere to a curfew pending further court appearances.

The next would not be until 30 days from his February 5 hearing at the earliest, said his public defender, Michelle Peterson.

Forcibly hospitalised petitioner deemed ‘mentally ill’ finally declared well enough for jail

Insisting that he did not intend to injure the officer, Bai emphasised that violence was not in the vocabulary of petitioners.

“We wouldn’t intend to cause harm to American society, create chaos or go out on the street assaulting people – I’d have to be crazy to do that,” he said, adding cheerily that no psychological issues were flagged in the mental health assessment he was ordered to take as part of his bail agreement.

Pending trial, Bai must wear an ankle monitor, not approach any Chinese government official or institution and stay away from Washington unless required to appear in court – conditions he resents but has pledged to honour.

“I love the United States and I respect American police officers,” he said, before pulling up “happy memories” on his phone: photographs of him standing beside police officers at various protests. All smiles and thumbs-up, the images appear somewhat poignant in light of Bai’s current predicament.

His reverence for the US – which he calls “the country with the best human rights in the world” – was forged by his experiences with China’s petitioning system, in which he said he had “lost all hope” by March 2016, when he decided to flee.

Though Chinese citizens’ rights to petition government officials are enshrined in law, their success rate is extremely low, said Frances Eve, deputy director of research at the Network of Chinese Human Rights Defenders.

The system, she said, was often a last resort for those who did not have the understanding or resources to pursue a case administratively – through the courts.

More often than not, petitioners make headlines not for winning a case but for suffering mistreatment at the hands of authorities eager to wash their hands of trouble or, having exhausted all petitioning channels, for resorting to desperate measures such as acts of violence.

Rather than a functioning mechanism for airing complaints, which often revolved around housing and land issues, the petitioning process had become something of a shield for the government to deflect criticism of China’s human rights record, Eve said.

“There’s this element of this government narrative that the petitioning system works, the justice system works, people can have redress for complaints,” she said.

While data on petitioners in China is scant, Eve said there were “countless cases” of petitioners being intercepted at transit stations, held in temporary holding centres and being forcibly returned to their place of origin at the behest of provincial governments, who did not want local grievances to garner the attention of central government.

Those who persisted risked being prosecuted for illegal petitioning, a nebulous category of offences that could include “gathering a crowd to disrupt order of a public place” and “creating a disturbance”, Eve said.

The fate of petitioners back in China weighs heavily on the mind of Wang Chunyan, a 55-year-old petitioner from the northeastern city of Dalian who came to the US in 2016 and is awaiting political asylum. Since then, from her home in New York, she has spent much of her time protesting the forced evictions carried out by local Chinese officials.

“I’m not just representing myself,” she said. “I’m also representing the brothers and sisters back in China whose property has also been seized. I’m seeking justice on their behalf. They have no channels through which to petition.”

Wang fled China after several spells of imprisonment, which she said resulted from her persistent petitioning of the local Dalian government over what she said was her family’s forced eviction from their home.

A former worker in an electrical substation in China who now works as a nanny in New York, she was also conducting a protest in Washington on the first day of trade talks, just hours before Bai attempted to block Liu’s car.

Screaming “Give me back my property, Liu He” as the vice-premier left his hotel, Wang joined a handful of petitioners who attempted to deliver their own letters of complaints to him.

At one point, she fell and attempted to grab Liu’s leg before being trampled by Secret Service officers who scrambled to fend off the protesters and rush Liu into his vehicle.

“He paid us no notice at all,” Wang said. “He didn’t pay any attention to the injustices we – Chinese people – brought to him.”

Rare disclosure sheds light on plight of China’s petitioners

By her own admission, Wang has never successfully delivered a letter to a visiting Chinese dignitary, nor has she witnessed any other member of the US-based petitioning community doing so.

The last known time, she said, was in September 2015 when a secretary travelling in the motorcade of President Xi Jinping accepted a letter from a protester during a state visit to Washington.

“They took the letter of complaint,” she said, “but for reasons we don’t know nothing came of it.”

Despite the palpable rage in his voice as he recounts his alleged persecution in China, Bai appears to have accepted the fact that – even if he had successfully broken passed armed police that day and if Liu had accepted his letter – his complaint likely would have fallen on deaf ears.

“Be you Liu He or Li Keqiang, I don’t care whether or not you pay us petitioners any attention, whether or not you engage with us or wish to solve our problems,” he said, his voice rising.

Even if officials do not respond on his petitioning, he continues to hope his story will be heard. “At the very least,” he said, “I will make it known to you the injustices I have suffered in China.”