If we're going to examine this question, it's necessary to establish some objective criteria for what constitutes judicial corruption. In the broadest possible terms, we could say that judicial corruption involves judges being unduly influenced to make their decisions, either through bribery or political pressure. In some countries, for example, where there's no independent judiciary to speak of, it's common for judges to hand down decisions in court cases, not according to the rules and norms of justice, but in accordance with how the government expects them to act. In such cases, if the demands of justice conflict with those of the government, then the latter will prevail.
In contrast to political pressure, which of its nature tends to come from governmental authorities, the bribing of judges is largely practiced by private individuals and organizations. This is a much more common practice than political pressure in countries such as the United States, where there's a formal separation of powers. In most cases involving bribery, corrupt judges will be offered sums of money in return for a favorable verdict. Sometimes this can result in a lesser sentence, at other times, an outright acquittal.
A recent survey showed that 50% of those polled thought that the American judiciary was corrupt. A report by the anti-corruption organization Transparency International further found that 15% of those interviewed admitted paying bribes to judges. This is more than double the number that reported paying bribes for access to public services in general.
A scholarly paper by Professor Stratos Pahis in the Yale Law Journal appeared to confirm these findings, purporting to show that judicial corruption is endemic throughout the United States. What seems to be the biggest problem is not so much the actual incidents of corruption or their frequency, but the lack of appropriate mechanisms in place to prevent them from happening and to punish those found responsible.
The vast majority of American judges are undoubtedly fine, upstanding public servants. But on the basis of Professor Pahis's article and other available evidence, it would appear that the problem of judicial corruption in the United States lies in how the system is structured, rather than in how many rotten apples there may be at any given time.