Lancashire Constabulary and Trading Standards are stopping vehicles on Morecambe Road, in Lancaster this morning.
An officer at the car park between Aldi supermarket and Babar Elephant restaurant said the stops were to check for correct trading and business licences.
Police, VOSA (Vehicle and Operator Services Agency) and Trading Standards are carrying out routine roadside checks on vehicles this morning.
The three agencies are working together to check that vehicles are correctly taxed and insured, vehicles are roadworthy and traders are treating their customers fairly.
For any traders that are stopped, Trading Standards are offering advice on fair trading, especially for businesses that should be providing cancellation rights to consumers they are carrying out work for.
County Councillor Janice Hanson, cabinet member for public protection, said: “Trading Standards receive hundreds of complaints each year about home improvement work carried out by rogue traders, who often cold call and persuade consumers to have work done which is unnecessary or overpriced.
“This type of operation allows us to identify and advise businesses who are operating in the area on the relevant laws to ensure consumers are effectively protected, and to disrupt the activities of rogue traders.
“Legitimate traders welcome these checks as unfair competition from rogue traders is hugely detrimental to the business of those who are trading fairly and abiding by the law.
“This operation is one of a number planned to take place across the county in coming weeks.”