Police objections to taxi licences in south west Scotland have more than trebled in the past three years.
The chief constable opposed more than 40 applications submitted to Dumfries and Galloway Council since 2007.
The objections were lodged on the grounds that would-be drivers were not "fit and proper" to drive a taxi due to previous convictions.
Offences cited included human trafficking, assault, possession of drugs and carrying a bladed weapon.
The figures and details of the crime concerns raised were obtained in a freedom of information request by the BBC to Dumfries and Galloway Council.
They show that the total number of taxi driver licence applications had risen by 25% from 342 in 2007-08 to 429 in 2009-10.
Police objections have gone up more steeply in the same time period from seven to 23.
The number of bids to become a taxi driver being rejected has also increased in line with that trend.
However, the local authority has still granted more than half of the licences opposed by the chief constable.
The previous convictions which have resulted in an application being refused are varied.
Many are motoring offences like careless driving, speeding or using a mobile phone while at the wheel.
Others include assault to injury, misuse of drugs, fraud, breach of the peace and attempting to pervert the course of justice.
The number of licences opposed by police is just a little more than 4% of the overall number of applications.
A Dumfries and Galloway Constabulary spokesperson said: "Our job is to protect the public.
"We would be failing in that duty if we do not voice our unease on any individual who gives rise to concern and wishes to work with the public.
"The final decision whether to grant or refuse the licence is made by the appropriate area committee of the council."
* The 22 licences were refused due to the following convictions: speeding, assault (2), attempt to pervert the course of justice, breach of the peace (2), driving while disqualified (2), driving without insurance (2), vandalism, driving with excess alcohol, possession of cannabis, having a bladed weapon in a public place, assisting unlawful immigration, taking and driving away a motor vehicle, misuse of drugs, careless driving, driving without a licence, falsifying tachograph records, fraud and using a mobile phone while driving.