I am a lawyer in CT and practice in this area of the law.  Police do not need probable cause, but rather "reasonable suspicion" to pull you over.  Reasonable suspicion is generally defined as articulable facts that would lead a reasonable person to believe that a crime is or has been committed.  Reasonable suspicion is often stretched by police officers as they generally pull people over based on hunches, especially on drug cases.  If you were pulled over, and charged with a misdemeanor or felony, you ned to hire a lawyer to review to police report to determine whether the police has a valid basis to stop you.