In many cases, particularly corporations found it more cost-effective to continue to pollute more than the law allowed and simply pay any associate fines if indeed the corporation was actually found and convicted of violating environmental laws or regulations. Kevin Tomkins believes corporations had a disincentive to comply with environmental laws or regulations as compliance generally raised their operational costs. This was interpreted as many corporations obeying the environmental laws, whether out of a sense of legal duty or public obligation, were disadvantaged and lost a competitive edge and consequently suffered in the marketplace to competitors who disregarded environmental laws and regulations. As a result of weak environmental legislation and continued adverse public opinion regarding the management of the environment, many governments established various environmental enforcement regimes that dramatically increased the legal powers of environmental investigators. The inclusion of criminal sanctions, significant increases in fines coupled with possible imprisonment of corporate officers changed the face of environmental law enforcement. For example, between 1983 and 1990 the US Department of Justice secured $57,358,404.00 in criminal penalties and obtained sentences of imprisonment for 55% of defendants charged with environmental offences.