He does not, however, trouble to conceal his humble origins. In conversation he is apt to hike his suit trousers way up, following a summertime habit among Chinese working men seeking to cool their calves. And he attributes his squat physique to his childhood diet.
"I come from a peasant family," Mr. Liu explains. "I grew up eating sweet potatoes, and now I look like one."
His peasant origins have left another lasting influence, he says: sympathy for "ordinary people at the bottom of society who are so helpless." And that was what motivated him to devote part of his law practice to a free legal-aid clinic for migrant workers.
There are 210 million such workers in China who have left their farms to build the roads, railways, and cities that have spurred this country's breakneck economic growth and to work in the factories that have sprung up in their wake.
Chinese law, though, makes them second-class citizens – denied the social welfare benefits their urban cousins enjoy – and employers routinely exploit them.
In May, 19-year-old migrant worker Li Hai threw himself to his death from the roof of a building at electronics manufacturer Foxconn, which makes Apple's iPad tablet computers, in the southern boom town of Shenzhen. He was the ninth company employee to kill himself this year.
"It's a constant problem," says Liu, explaining why he chose to help migrant workers rather than victims of China's myriad other social injustices. "That means we can work on it systematically."
Liu did not always think like this. When he founded his law firm in 1999, he recalls, "I just wanted to grow my business as much as possible and to make it as successful as possible. Those were my only ambitions."
But some of the cases he came across, including blatant pressure from local government officials on judges to rule in their favor in cases brought by aggrieved citizens, made him ponder the injustices of a society where the gap between rich and poor was widening.
"I was very unhappy with a lot of policies, but I learned that being unhappy doesn't help, complaining doesn't help," Liu says. "I had to work on real issues, and start with little things."
So in 2002 Liu rented the floor above his law offices in a tower block on Jinan's main street, set up a ping-pong table in the new legal-aid clinic's waiting room, began distributing fliers and booklets explaining migrant workers' rights at factory gates and construction sites – and then waited for customers.
Not all of the 54 lawyers at Liu's firm agreed with his new direction. "But I yelled at them" and the dissenters came around, he says with a laugh. "I have a very strong personality."
Since then the clinic has helped more than 30,000 migrants recover nearly 5 million renminbi ($735,000) in unpaid wages, he says.
As China muddles its way toward the rule of law, rather than that of arbitrary officials, lawyers are playing a key role, Liu says. "Thirty years ago we just represented our clients in lawsuits. Today we take part in politics and pay attention to ordinary people's well-being."
Wealthy lawyers have a special responsibility, he argues, pointing to a framed piece of calligraphy on his office wall that he says "is the philosophical basis for what I am doing."
It is a saying from Mencius, a 4th-century BC Chinese philosopher in the Confucian tradition: "If you are poor, polish your virtue; if you are successful, help save the world."
At the practical level, that might mean offering legal advice to a man like Zhu Shengguan, a worn-looking migrant worker who came to Liu's office recently, kneading the mangled stumps of two fingers he had lost in a construction site accident.
Mr. Zhu's employer had tried to deny having anything to do with him before eventually paying his medical bills. Zhu was too ignorant of the law to have filed his appeal on time against what he thought was inadequate court-ordered compensation. Liu offered to represent him in the appeal Zhu's employer had filed seeking to lower the compensation still further.
Once, trying to obtain unpaid wages made up the bulk of the clinic's work. Today Liu's team of five lawyers spends most of its time on labor disputes or helping workers whose employers have refused to pay their social security contributions or to give them a contract.
Out of such small, day-to-day cases Liu hopes to build the rule of law in China. He acknowledges that the results can be limited and that progress sometimes seems slow.
By the front door of his offices hangs another piece of ancient calligraphy proclaiming the three principles that Liu says should guide a lawyer's work: "natural justice, national law, the people's feelings."
In China, though, "natural justice" and "national law" do not always coincide, especially when it comes to migrant workers.
"The purpose of what I am doing," Liu says, "is to bring national law into line with natural justice."
But he picks his fights carefully, and his instincts are to stay on the safe side.
"Natural justice is the highest value," he says, "but when it conflicts with national law, I quit. I do not fight against the law. If you are too radical, you get marginalized. It's better to stay in the mainstream and try to change things gradually.
"Promoting the rule of law is a long process, and we can't be in a hurry," he argues. "But each time we help one migrant worker to use legal measures, that influences a group of people around him.
"It doesn't sound spectacular," he says, "but in the long term it will have a big impact."