The legality of competitions and draws featured on quiz channels like ITV Play and shows like This Morning has been questioned by the gambling regulator.
ITV launched its dedicated digital quiz channel in April
The Gambling Commission has launched a public consultation into such quizzes following complaints from viewers.
"The law is unclear on the distinction between lotteries, prize competitions and free draws," said Tom Kavanagh, the commission's deputy chief executive.
Organisers, he said, could be running "unregulated and unlicensed lotteries".
The Gambling Act 2005, which comes fully into force in September 2007, makes a distinction between a skill competition and a lottery.
The former, it states, should include a skill element that deters a proportion from entering while eliminating a proportion of those that do.
Some TV quizzes, like those featured on This Morning and Richard and Judy, signal which answer is correct by featuring two plainly incorrect multiple-choice alternatives.
Mr Kavanagh said the consultation was only a discussion document and that the commission was "not out to stop people enjoying properly run competitions".
"Prize competitions and free draws are, and will remain, free of statutory regulatory control."
There are around 15 digital quiz channels in the UK, including ITV Play and the Channel 4-owned Quiz Call. A number of channels include similar programming in parts of their schedules, including ITV1, ITV2, and Five.
Some viewers have complained about their use of premium rate telephone numbers, which charge callers whether they get through to the host or not.