Final answer:
Police unions can impact the power dynamics within a police department by limiting the disciplinary authority of police chiefs through negotiated contract terms governing personnel decisions and disciplinary procedures.
Step-by-step explanation:
The question asks for an example of the impact of police unions. Among the choices given, an increase in the funds available for grievance litigation, a reduction in the power of police chiefs, and an increase in citizen involvement in police politics do not typically represent the direct impacts of police unions.
However, a reduction in the power of police chiefs is indeed an impact that police unions can have. Unions often negotiate terms that limit the authority of police chiefs over personnel decisions. For example, union contracts may mandate certain disciplinary procedures or appeals processes when an officer faces allegations of misconduct, which can restrict the power of chiefs to discipline officers swiftly or unilaterally.