For the past couple of years both employees and employers have sporadically raised the issue. And this week the BBC screened a documentary featuring one PR agency that allegedly uses 20 unpaid interns .
It is not difficult to see why firms opt for unpaid interns. There is a glut of talented youngsters produced by our universities, who are struggling to get jobs and willing to try anything to get their first step on the career ladder. Equally, recession-hit employers are striving to protect margins at a time of sluggish revenues. Workers who cost little - often nothing - and without employment law strings attached become a very tempting proposition.
One could argue the phenomenon is simply employment market forces at work, and therefore justified in a tough market. But there are two main problems with the practice.
The first is that it is ethically wrong to employ anyone who, over several months, is adding real value to one's business, without paying them properly.
The second is that, in the long term, the practice mitigates against valuable industry diversity. The only youngsters who will be able to work for periods without pay will be those from wealthy families - and probably those whose parents own large residences near metropolitan areas. As a result the PR industry will become even more homogenous than it already is.
Now even if you don't believe that social mobility is desirable per se, it is a problem because PR's great strength is its ability to connect diverse organisations with diverse audiences. Homogeneity mitigates against constructive conversations with different demographics, something that the advent of social media has made more critical than ever.
There is certainly nothing wrong with offering work experience. It can be a great way for young people to work out which career they would like to pursue, and for employers to discover bright new talent.
But if they are employed for more than a couple of weeks they should be paid the minimum wage and the terms should be transparent.
The CIPR has some good work placement guidelines on the policy section of its website - cipr.co.uk.
Before the recession, spiralling salary inflation was the scourge of PR firms, but now we have the reverse problem at the certain levels. The pursuit of professionalism means treading the middle ground.