The constitution says that the person has a right to a fair and speedy trial by jury. Not prosecutors. Jury. In case you don't know the seventh amendment here it is. "In suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall be otherwise reexamined in any court of the United States, than according to the rules of the common law."
It seems that California does not want to let a grand jury decide if a police officer should be charged with a crime in officer involved shootings. Since what happens in a grand jury room is not open to the public, many are frustrated by the secrecy. However, police officers are entitled to the same treatment and confidentiality as any other citizen.
Sometimes the people who have the power of the badge are the people who abuse it the most. There is one set of laws for people who are police officers and their friends, and another set for the rest of us. Prosecutors should determine if police officers should be charged with a crime because they break the law more than anyone else.
The constitution was not written to indicate how a person is to be charged, regardless of if that person is enforcing said constitution, except in the case of the President Himself. The constitution guarantees only the right to a fair trial once the charges have been presented, and this has been enough to ensure the vast majority of the people of the United States are charged fairly as well, for over two hundred years, regardless of who presents these charges to whom.
No, I don't feel that it's unconstitutional. In California, prosecutors have to determine if a police officer should be charged with a crime. This makes sense to me. Officers are not above the law. Police brutality, and worse, is very real, and it needs to be curbed. In some cases, charging an officer with a crime is justified.