There are two methods of corruption of the judiciary: the state (through budget planning and various privileges), and the private. Budget of the judiciary in many transitional and developing countries is almost completely controlled by the executive. The latter undermines the separation of powers, as it creates a critical financial dependence of the judiciary. The proper national wealth distribution including the government spending on the judiciary is subject of the constitutional economics. Judicial corruption can be difficult to completely eradicate, even in developed countries.
Why is it problematic to have the executive branch control the judiciary's funding?
undermines the separation of powers