Democracy has 3 pillars
1. Legislature
2. Executive
3. Judiciary
All these are independent of each other and puts a check on each others going beyond its limit.
Executive actions can definately be challenged in court
Laws passed by legislature can also be scrutiniesed by judiciary
but is there any check on judiciary?
Why should we put any check on judiaciry?
The first reason can be because judges are also human and can commit mistakes.
But there are some other reasons also
According to report by Transparency International (TI) called the “Global Corruption Report 2007″
1. 77% believe that the Indian Judiciary is corrupt
2. Money was paid to the officials in the following proportions: 61 percent to lawyers; 29 percent to court officials; 5 percent to middlemen

Further
3. In January 2002, S.P. Bharucha, then India’s chief justice, said that 20 percent of the higher judiciary might be corrupt. In recent years, several upper court judges have been accused of “irregularities”, for instance, in the preferential allotment of valuable land by state governments, and other favours
4. Judicial corruption in India is attributable to a number of factors, including “delays in the disposal of cases, shortage of judges and complex procedures, all of which are exacerbated by a preponderance of new laws”

Inspite of all these
1. the RTI is not applicable to judiciary (As per CJI, TOI 20-4-08)
2.In India, impeachment is not feasible because it requires a huge (two-thirds) majority in Parliament (V. Ramaswamy, a Supreme Court judge, was found culpable by a court committee. But he was politically well-connected and could not be impeached.)

I agree that there are several genuine problems like low ratio of judges per one million population. This is as low as 12 to 13 in India, compared to 107 in the U.S., 75 in Canada and 51 in Britain and there are no easy solutions to the problem of making judges accountable. But some measures can be
tried. One is to appoint judicial ombudsmen from two highly-regarded statutory bodies, the Election Commission and Comptroller and Auditor General (CAG) of India. Nothing prevents the CAG from initiating an independent review of the performance of the judiciary. The CAG could produce highly credible and objective reports and help kickstart a process of promoting transparency and accountability.”