Introduction The United States is the country where domestic violence and homegrown extremism turn out to be a serious criminal problem. Though numerous criminal laws are developed at local, state, and federal levels in regards to the US Constitution, it seems they are not enough to promote an effective and properly working criminal justice system in the country. Each level of the system has its peculiarities and mechanisms with the help of which safety of citizens can be promoted, and law enforcement leads to successful results. Still, the acts of domestic terrorism continue happening in the United States, and, in most cases, this terror is a part of right-wing extremism with Whites, not Muslims, as the main American terrorists (Ruiz-Grossman, 2017). Today, it is not enough to recognize the problem of domestic terrorism and discuss it at different levels. In this paper, in addition to the discussion of the US criminal justice system, a solution on how to train leaders who may influence criminal justice policies will be developed regarding recent criminal cases, studies, and conclusions offered through the media. Domestic Terrorism and Homegrown Extremism The threat of terrorism is real for the United States, as well as for other Western countries, and results from radicalization when leaders try to deepen their influences and make fast instead of rational decisions (Hafez & Mullins, 2015). Since the events of 9/11, it was decided to pay much attention to the strategies which protect the US population and involve as many possible law enforcement agencies. Domestic terrorism is not only a serious threat to the national security that has a form of physical violence, but a collection of tactics in terms of which isolation, the destruction of self-confidence, and the development of fear are possible (Pain, 2014). Extremism is another crucial concept in the criminal justice system of the United States that includes all possible actions and ideologies that contradict the already established rules, morals, and standards. Tierney (2017) explains homegrown extremism as a situation close to terrorism when a person or a group of people are radicalized in order to commit violence at their home or visit other countries to be foreign fighters. In other words, homegrown extremists are the people who believe that violence is the best solution to support their ideologies against their own countries. Regarding the nature of such cases of terrorism, it is very difficult for local authorities and agencies to deal with potential terrorists due to their location, cultures, roots, and driven ideologies. Law Enforcement Agencies To learn what kind of work has to be done to deal with domestic terrorism and homegrown extremism, the nature and the role of law enforcement agencies have to be considered. In the United States, these agencies include all governmental organizations which aim at enforcing laws according to which any anti-government violent activities of native citizens (not radicalized Muslims) have to be investigated, analyzed, and prevented if it is possible (Kurzman & Schanzer, 2015). Active campaigns have to be regularly developed because of some new reasons, conditions, and outcomes may be observed and become a serious threat to one group of people o