In the European Parliament, she was a leading member of the Environment Committee and between 1999 and 2004 was Chairman of the Committee on the Environment, Consumer Protection and Public Health. During her chairmanship she tried to focus attention as much on Member States' performance in transposing and applying new EU laws as on the adoption of more such laws. This was during a period of very intense legislation in the area of water and air pollution, waste disposal and controls on chemicals. Jackson controlled the committee firmly but with humour – qualities very necessary when German opponents of new laws on alternative medicines attempted to control proceedings in 1995. It was noted that on 11 September 2001 Jackson's committee was the only one that did not adjourn when the news of the attacks on New York came through: Jackson argued that abrupt abandonment of the Committee's work would have been another small victory for the terrorists. Jackson has been described by Liberal Democrat MEP Chris Davies thus: "She's been here forever: a bit 'jolly hockey sticks' but firm, fair and funny."