In "True Justice" Mr. Stevenson says that defending innocent people is more difficult, what is the reason he gives for this?

Executive Director of the Equal Justice Initiative, a human rights organization in Montgomery, Alabama. Under his leadership, EJI has won major legal challenges eliminating excessive and unfair sentencing, exonerating innocent death row prisoners, confronting abuse of the incarcerated and the mentally ill, and aiding children prosecuted as adults.

Mr. Stevenson has argued and won multiple cases at the United States Supreme Court, including a 2019 ruling protecting condemned prisoners who suffer from dementia and a landmark 2012 ruling that banned mandatory life-imprisonment-without-parole sentences for all children 17 or younger. Mr. Stevenson and his staff have won reversals, relief, or release from prison for over 135 wrongly condemned prisoners on death row and won relief for hundreds of others wrongly convicted or unfairly sentenced.

Mr. Stevenson has initiated major new anti-poverty and anti-discrimination efforts that challenge inequality in America. He led the creation of two highly acclaimed cultural sites which opened in 2018: the Legacy Museum and the National Memorial for Peace and Justice. These new national landmark institutions chronicle the legacy of slavery, lynching, and racial segregation, and the connection to mass incarceration and contemporary issues of racial bias. Mr. Stevenson is also a Professor of Law at the New York University School of Law.

freedom of speech is also protected by the 1 amendment.

explanation:

here is pretty much what the 1st amendment says:

congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.