The mother of a man executed 20 years ago for a murder to which another person later confessed appeared in a Chinese court Monday, as pressure builds to correct errors of justice.

The court's reopening of the case of Nie Shubin, executed by firing squad in 1995 at the age of 20 for rape and murder, comes just a week after another court declared innocent a teenager executed on the same charges in 1996.

The ruling Communist party is trying to ease the resentment caused by mistaken verdicts, which are fuelled by police reliance on forced confessions and the lack of effective defence in criminal trials.

On Monday last week a court in China's Inner Mongolia region declared innocent Hugjiltu, who had been executed at age 18 in 1996 for murder and rape. Doubt was cast on the original verdict when another man confessed to the crime in 2005.

Nie's family has been campaigning for justice without success since a serial murderer arrested in 2005 confessed to the killing for which their son was convicted.

The country's high court this month ordered authorities in Jinan, the capital of Shandong province, to reopen the case.

Nie's mother Zhang Huanzhi, 70, entered court Monday flanked by lawyers and court officials.

"The old lady had a lot to say," one of her lawyers Chen Guangwu said of the meeting. "Its not easy to meet with a judge, so of course she wanted to speak."

Chen said court officials promised to allow lawyers access to the original case files used to convict Nie, but had not given a precise date.

"We said this was a key test case for the idea of rule of law," Chen said. "This is a good time for the revision of past mistaken judgements."

Dozens of people surrounded the court to air grievances at the legal system, shouting and waving banners accusing it of mistaken judgements in a variety of cases.

One of the judges responsible for reviewing the case also sat on the appeal panel for disgraced politician Bo Xilai, Chen added.

But lawyers cautioned that the path to exonerating Nie could be long.

"We have just covered the basics. The next step is to reinvestigate the case," said family lawyer Li Shuting.