When police officers witness domestic violence they are required by law to make an arrest. They had more than enough probable cause to arrest Monica Jarrow, by not arresting her Detectives Winter and Jaruszalski were actually violating the law.
There is no city in Oregon called Brandon. There is however a city on the Oregon coast called Bandon that has a beach-side golf course. However Bandon isn't on the northern Oregon coast like "Brandon" is shown to be, Bandon is on the southern Oregon coast about 90 miles north of the California border.