If a police officer is talking to you, chances are, you’re already in trouble, whether you know it or not. If it’s something more than a simple traffic stop and you are not the victim of a crime, the police are eventually going to 1) ask for consent to search you, your vehicle, your house, or your belongings, and 2) talk to you about the crime they suspect you’ve committed.
You can ALWAYS refuse consent to search, unless you’re on probation (talk to your attorney about the complicated issues of consent and probation for more information.) Be respectful but firm. When the police officer asks why, just tell them that you don’t consent to searches. Repeat it. Don’t go into detail. Look up the explanatory videos on FlexYourRights.org for more info.
You can also refuse to talk to a police officer, and remaining silent is a very good idea. Ask if you’re free to leave. If they say yes, then leave. If not, tell them you want an attorney before you are questioned any further.
Police can certainly treat you differently for invoking these constitutional rights. They can threaten to bring in a drug dog, or tell you if they find contraband, they’ll put you in jail instead of giving you a citation to appear out of custody at a later time. But you are guaranteed these rights by the federal and Oregon constitutions, and the State cannot use the fact that you exercised your rights as evidence against you.