The primary internal conflict Steve experiences revolves around his identity. Throughout the story, Steve wrestles with his conscience and struggles to recognize who he is as a person. Steve questions his morals and tries to justify his actions. In prison, Steve expresses his conflicting feelings in his diary and continually examines himself in the mirror. Steve replays the day of the crime, contemplates his true intentions, and attempts to rationalize his entire experience. He regrets even being associated with criminals like James King and believes that he is genuinely a good person. However, Steve struggles to acknowledge his true character and questionable morals. Although he states that he is innocent, there is evidence to suggest otherwise. Even after the trial, Steve continues to search for his true identity by filming himself from different angles and questioning his morals.

While there are many external conflicts in the novel, the primary conflict in Monster is within Steve. Steve is placed in opposition to numerous elements of the criminal justice system and to society overall. However, what matters the most in terms of his position as protagonist is his ability to hold onto his identity. Walter Dean Myers reveals Steve’s numerous struggles as the boy reflects on his activities before he was arrested as an accomplice. The author emphasizes the importance of creativity for Steve, who finds a crucial outlet in his writing. He must find a way to cope with the massive pressures he faces as others oppress him with their label of "monster." Furthermore, this creative outlet must have future-oriented dimensions, as Steve knows that long-term incarceration might be his future.

While Steve realizes that his dream of making films must be put on hold as he focuses on acquittal, he does not abandon that dream. The internal conflict is shown through the doubts that his story often raises about whether he can sustain this fundamental optimism or whether he will succumb to despair in the bleak surroundings. The support that his film teacher offers in court helps Steve cling to his hopes, but only he can finally achieve a positive sense of self.

I would argue that there are two equally strong conflicts in Dean's book Monster.

First, Steve is on trial for being an accomplice to a robbery that turned into a murder. Most of the book centers around his trial and various testimonies. One interesting facet of this conflict is that it is never fully resolved for the reader. Although Steve is found not guilty, the reader is left wondering whether he really did act in conjunction with King, sweeping the store they robbed to make sure no one was inside. Following the verdict, Steve's own attorney stiffens when he tries to hug her, and he is left wondering what she truly sees in him. This external conflict of Steve vs. society is perhaps due to Steve's own actions—and maybe not.

Second, Steve battles internal conflict from the very beginning. In the jail, he doesn't recognize himself in the mirror, metaphorically representing that he doesn't fully recognize the person he's become. Is this because he was actively involved in the murder or because of the way society views him? Five months after the trial concludes, Steve is still struggling with whether his lawyer views him as a "monster," and he is still trying to find some inner peace. Again, his inner conflict is not resolved with the plot's conclusion. There are no easy resolutions to be found with the conflicts in Monster.

The main conflict in Monster concerns Steve Harmon's loss of identity. Throughout the novel, Steve is referred to as a "monster" by the prosecuting attorney. Like many other teenage minorities caught up in the justice system, Steve fits the stereotype and is automatically viewed as a criminal before the trial begins. Steve is placed in a violent detention center where he fears for his life every day. As the novel progresses, Steve's confidence diminishes, and he begins to wonder if he really is a "monster." Steve also questions his morals and is unsure about who he truly is. At the end of his trial, Steve is found not guilty and attempts to hug his attorney, Kathy O'Brien. However, instead of hugging Steve, O'Brien turns away from him. This gesture deeply upsets Steve, and he wonders if she viewed him as a "monster." Steve spends the rest of his days as a free man filming himself, trying to find his true identity. 

The main conflict of Walter Dean Myers' book, Monster, is about a teen accused of murder trying to clear his name in both the legal and social settings.  Steve is 16 years old and claims to be at the wrong place at the wrong time, and claims to be the victim to inaccurate eyewitness accounts.  Steve must also deal with the most frightening nature of the justice system.  Steve's conflicts are primarily settled in the domain of an individual against a social order. Steve's battle to prove his innocence is the major conflict within the novel.

In addition to this, we never really know if Steve is innocent or guilty.  The journal/ script aspect of the novel makes it upon us to think about such an issue.  Perhaps, this is another conflict of the novel, only this one is left for us to analyze.  This question has been asked before and you can check out that answer and compare it to this one.