In the oregon law, if you read it, it does require that psychologists go through a specific training program including pharmacology & psychopharm & such.
Actually if you ask me, that type of training can make more sense than the typical M.D. program, if the psychiatrist were only doing something as light as outpatient for non severe mental illness (not commitable, person is still able to function in society by themselves). I've often questioned the use of memorizing 10,000 histo slides in psychiatry.
However even with such training, such a psychologist would not be ready for hospital consultation, nor dealing with psychiatric patients whose medical problems are heavily interacting with a medical problem such as Conversion DO, Pseudoseizures, Clozaril use, required polypharmacy, Hep C patients requiring medication etc.
And I will add, unfortunately so too are not a lot of psychiatrists ready for such. Several psychiatrists as well as many other doctors in all fields tend to get lazy after residency, and forget their stuff. I've seen several psychiatrists where I look at their choice and meds and think to myself "WTF!". Half the time I get a patient transferred from another unit to my own, I check out their labs, see a cholesterol of 260, and the psychiatrist did nothing about it. They didn't even bother to ask the IM doc to check it out.
One thing that I've felt made clinical psychology superior to psychiatry training is being able to adopt a model looser than the medical model, and having more training in psychotherapy. IF you got 10 psychiatrists and ask them who Marsha Linehan is, I'd bet at least 5 of them would not know how to do it. I've yet to meet any psychiatrist who has yet done DBT for real, and knows how to do it, and their knowledge is more than superficial -its the treatment for Borderline PD- to satisfy the board exam.
So having more psychologists work with us, that's something I want. I worked in a health system in residency that didn't have someone with whom could refer Borderline patients. Everytime they got a Borderline, the staff & attendings kept whining "oh another Borderline", and no one was giving these people DBT or making a referral for such.
Having worked with a psychologist on my treatment team, its very good to have one (at least the ones I've had). Its great to ask them to do an MMPI, MFAST, SIRS, etc and be able to discuss the results. Its nice to have a psychologist on the staff that actually knows how to do DBT for real and does it, and you start seeing benefits from the DBT on your borderline patient, or a psychologist starting a behavioral treatment plan--having specific behaviors you want to see from the patient, and having that psychologist track the behaviors on a daily basis.
Overall, I'm against the idea of psychologists being able to prescribe, except maybe in a situation where the law specifically stated--no polypharmacy, only for non severe mental illness, only for mental health reasons, and only on meds with an extremely large safety margin (no lithium, no Depakote), and add to that--no hospital consultation, no inpatient, no meds that require labwork (heck that's almost all of them!), unless that psychologist were working hand in hand with a medical doctor who was overseeing the labs. I doubt many medical doctors would want to do that with a psychologist unless that doctor were in a family practice/PCP clinic that could not get their hands on a psychiatrist.