This excerpt taken from the PBR 20-F filed Jun 30, 2005.
If a State of Rio de Janeiro enforces a law imposing ICMS on oil upstream activities, our results of operations and financial condition may be adversely affected.
In June 2003, the State of Rio de Janeiro enacted a law, referred to as Noel Law, imposing the Imposto sobre Circulação de Mercadorias e Serviços (state sales tax, or ICMS) on upstream activities. Although the law is technically in force, the government of the State of Rio de Janeiro has yet to enforce it. Currently, the ICMS for fuels derived from oil is assessed at the point of sale but not at the wellhead level. If the State of Rio de Janeiro enforces the law, it is unlikely that the other states would allow us to use the tax imposed at the wellhead level in Rio de Janeiro as a credit to offset the tax imposed at the sale level. Therefore, we would have to pay ICMS at both levels. The constitutionality of this law is currently being challenged at the Brazilian Supreme Court. If the law is declared constitutional and the State of Rio de Janeiro enforces the law against us, we estimate that the amount of ICMS that we would be required to pay to the State of Rio de Janeiro could increase by approximately R$5.85 billion (U.S.$2 billion) per year. This increase could have a material adverse effect on our results of operations and financial condition.