Medvedev, a first deputy prime minister, said: "One of the key elements of our work in the next four years will be ensuring the independence of our legal system from the executive and legislative branches of power.
"We need to root out the practice of unlawful decisions 'by request' or for money."
He also repeated earlier promises to ensure personal freedoms and an independent and free press.
"We're talking about freedom in all its forms, personal freedom, economic freedom, and in the end, the freedom of self expression," Medvedev told the Krasnoyarsk Economic Forum.
Medvedev, 42, spoke more about the development of social welfare projects than international affairs or the resurrection of Russian military power, themes Putin addresses regularly.
On relations with the US, Medvedev emphasised co-operation rather than the two countries' differences over issues such as Kosovo and the proposed US missile defence shield in eastern Europe.
He said "in today's globalised world, when our states share, in effect, a common set of values, such co-operation should continue."
Medvedev also touched on the need to protect private property.
Critics of Putin's administration accuse it of flouting property rights by effectively renationalising private firms, especially in the oil sector.
Medvedev said: "Respect for private property has to be one of thefoundations of the government's policies.
"Today more often than not, the government itself is not taking measures to defend the rights of private property holders."
He also said the government should review its tax system and cut the burden in some areas to ensure that the economy, which last year grew by 8.1 per cent, can continue to grow.
"Our tax system must be competitive with tax systems of other countries," he said.
"The state should collect as much tax as needed to ensure that society functions effectively and our national businesses do not flee abroad, the economy doesn't fail."