The term "lateral" in reference to police officers usually has
to do with applicants for police officer positions. If a person who
is already a police officer in one agency wants to work for another
agency, he may be allowed to come into the second agency as a
"lateral" candidate. This means he may not have to attend another
police academy (or may be able to complete an abbreviated course)
and may start at a pay step above that of an entry-level officer.
Lateral-entry positions save the hiring agency money, as they don't
have to pay a candidate while they attend the academy, and they get
an officer who already has experience. It's usually easier to
"lateral" into an agency in the same state where you are already
certified, since the same training requirements usually extend
across the state. Some states and agencies will accept candidates
from other states if they can show their training is equal to or
exceeds the training in the hiring state.