Sir Peter Bottomley is part of the All Party Parliamentary Group on Drug Policy Reform, which is calling for cannabis to made legal for specific, medicinal purposes.
The Conservative MP for Worthing West does not support making the plant itself legal but backs making prescription drugs using chemicals contained in cannabis legal.
He argues that it doesn't make sense that paracetamol is available for low-level pain and morphine for high-level pain, but not cannabis for moderate pain.
Evidence has shown that cannabis can also help relieve anxiety, nausea and muscle tightness.
Other evidence has linked it to addiction, psychosis, and a lack of productivity. It's also claimed it can lead to people trying harder drugs.
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Speaking to Premier Sir Peter said: "At the moment I could be prescribed morphine if it was appropriate, I could take paracetamol for myself, but what I can't do is have my doctor prescribe something for me based on cannabis which is a proper evaluated medicine.
"Whatever else you can say about cannabis, it's not as heavy a drug as morphine.
"It seems to me blindingly obvious that you can have prescriptions at either end of the spectrum, that the middle of the spectrum shouldn't be empty."
A Home Office spokesman said: "There is a substantial body of scientific and medical evidence to show that cannabis is a harmful drug which can damage people's mental and physical health.
"It is important that medicines are thoroughly trialled to ensure they meet rigorous standards before being placed on the market.
"There is a clear regime in place, administered by the Medicines and Healthcare Products Regulatory Agency, to enable medicines, including those containing controlled drugs, to be developed."
Listen to Premier's Aaron James speak to Sir Peter Bottomley:
