Liberal Democrat Peter Black said he had helped several people win appeals against Swansea, Bridgend and Neath Port Talbot councils.
He was unhappy that GP evidence was no longer accepted as proof of disability.
The Welsh government said tighter regulations ensured consistency, but eligibility had not changed.
Concern about fraudulent use of blue badges led to a revamp of the system across England, Scotland and Wales in 2012.
Plastic badges with holograms replaced hand-written cards while local councils took over the running of eligibility tests from GPs.
Mr Black claimed this resulted in decisions being taken by council officers with no medical training.
“The guidelines say you need occupational therapists to carry out the assessments,” said the South Wales West AM.
“Not all councils have them but they don’t allow evidence from GPs. So council officers are making the decisions themselves.
“The blue badges have been abused but we need more latitude with some people who are clearly in difficulty,” he said.
Swansea council – of which Mr Black is a member – confirmed that rejected applications for blue badges more than doubled from 322 in 2010 to 679 in 2013, while the total number of applications fell from 6,809 to 6,243.
Rob Stewart, cabinet member for finance and resources, said the Welsh government had confirmed Swansea was running the blue badge scheme in line with its guidance.
A Welsh government spokesperson said: “Applications for blue badges are determined by local authorities.
“We introduced new regulations to ensure fairness and consistency in awarding of the badges, but these new regulations did not reduce or restrict the eligibility criteria for issuing blue badges.”