In August 2003, he was promoted to Minister for Internal Security in the
Somare government. He pledged to clean up the national Department of Immigration, claiming that some government officers were taking bribes to "turn a blind eye" to human-smuggling and gun-running, called for proper post-mortems to determine causes of death and prevent revenge killings for perceived "sorcery" and pledged to ban MPs from using police officers as private bodyguards. He proposed to change the constitution to allow Papua New Guinean police to deploy overseas on regional assistance missions, which would be supported by the parliament in January 2004. He also proposed introducing curfews on major highways and extending the term of the police commissioner to reduce political influence. In early October, he declared the police force was in "crisis" due to poor discipline, political interference, low wages and poor housing, and called for increased funding, the recruitment of 2,000 more officers, and a one-off aid assistance package from Australia to remedy a series of issues. He initiated a review committee to identify problems that could be tackled within the police force, and lamented that while low wages were causing major problems, the government could not afford a salary increase. In November, he announced that there would be no police recruitment in 2004 due to a lack of funds; however, following the December announcement of an Australian aid package, he announced that 400 officers could now be recruited. The proposed Australian assistance package also involved the deployment of 300 Australian officers, which saw Kimisopa involved with the passage of legislation surrounding the powers and liabilities of the officers, as well as defending them from claims that the deployment breached the country's sovereignty. He was subjected to particular criticism from some MPs for the proposed immunity for the Australian police. In March 2004, he was involved in the deployment of Papua New Guinean police to the
Solomon Islands, following the January passage of enabling legislation. Domestically, he continued attempts to limit the supply of firearms and ammunition within Papua New Guinea, ultimately proposing a total ban on the sale of guns. In September 2004, he called for new legislation to crack down on illegal immigration to Papua New Guinea. In late 2004, Kimisopa clashed with his own government over police funding, submitting a request for a 10-million-kina increase and lashing out at a budget that delivered a 10% cut in funding for 2005. He also repeatedly advocated for mandatory funding of police by provincial and local governments from their own budgets. His advocacy was successful, and in October won executive approval for a one-off 10% pay rise for police. In the same month, he announced that women would form half of the next intake of police recruits in an attempt to improve gender parity in the police force. In November 2004, he initiated a bill to regulate the security industry in Papua New Guinea, which was passed unanimously by parliament, successfully separated the pay structure for police from the other uniformed forces, permitting the police union to negotiate their own pay, and won executive support for the establishment of a gun control committee headed by former PNGDF commander
Jerry Singirok. In December 2004, as Australian police finally prepared to arrive in Papua New Guinea, Kimisopa argued that the five-year timeframe of the program should be doubled. He continued to be outspoken about the poor state of the police, declaring that corruption went "right to the top" and that "Chinese mafia have bought off officials throughout the system...they are siphoning money out, corrupting Government officials, colluding with police and making attempts to kill officials as well." In February 2005, he called for an amnesty for corrupt police who admitted wrongdoing and promised to reform, and suggested introducing a standing Police Complaints Tribunal if the situation did not improve. He also announced an urgent review of firearms legislation in Papua New Guinea in his ongoing campaign against illegal weapons. He also faced ongoing opposition to the Australian police deployment, with the
Police Association of Papua New Guinea calling for their removal and one-time ally
Luther Wenge launching a court challenge to the program. The
Supreme Court ruled that the enabling legislation for the Australian deployment was unconstitutional in May 2005, forcing Kimisopa to concede that the Australian police would have to leave the country. He labelled the ruling "devastating", declaring that the Australian assistance was vital for planned reforms to the police and suggesting a solution be found to "resuscitate" it. He flew to
Canberra later that month for negotiations with Australian officials, but faced problems around the issue of immunity for the Australian police. In July 2005, a long-planned gun summit was held in
Goroka to finalise a report on addressing illegal firearms, resulting in wide praise for Kimisopa's efforts on the issue. In late August he faced the international media over a
Human Rights Watch report about police abuses against children in Papua New Guinea, declaring that it was "something we cannot hide from" and again emphasising the need to reform in concert with Australian assistance. In September, a revised agreement was agreed with the Australian government, which Kimisopa criticised for its more limited role for Australian police and lower levels of financial assistance. ==Minister for Justice and 2007 defeat==