Consider this extraordinary figure: 30 percent of members of parliament have criminal cases pending against them…the answer to why political parties in India nominate candidates with criminal backgrounds is painfully obvious: because they win (see figure 1). In the 2004 or the 2009 parliamentary elections, a candidate with no criminal cases pending had—on average—a 7 percent chance of winning. Compare this with a candidate facing a criminal charge: he or she had a 22 percent chance of winning. Granted, this simple comparison does not take into account numerous other factors such as education, party, or type of electoral constituency. Nevertheless, the contrast is marked.
Writing at the Carnegie Endowment for International Peace blog, Milan Vaishnav goes on to note that those with criminal backgrounds appear to have ready access to cash and in addition their toughness appeals to voters:
In contexts where the rule of law is weak and social divisions are highly salient, politicians often use their criminal reputation as a badge of honor—a signal of their credibility to protect the interests of their parochial community and its allies, from physical safety to access to government benefits and social insurance.
…The appeal of candidates who are willing to do what it takes—by hook or crook—to protect the interests of their community provides some intuition for why the odds of a parliamentary candidate winning an election actually increase with the severity of the charges, with slightly diminishing returns in the most severe instances…