The PSNI has ordered a probe into why so few Catholics are applying to join the organisation amid serious concern over representation levels.
Recent recruitment drives have struggled to attract new Catholic officers, despite campaigns targeted specifically at the nationalist/republican communities.
Just 30% of those to apply to recent recruitment drives were from a Catholic background. And just over 20% of those to make it through onto the merit pool were Catholic.
Consulting firm Deloitte has been tasked by the PSNI to carry out research into the reasons behind the reluctance of Catholics to sign up.
Catholic police officers are a particular target for dissident republicans who have launched a number of attacks.
In October, a police recruitment event at a Londonderry hotel was cancelled after dissident republicans planted a bomb at the property.
Catholic police officer Ronan Kerr was killed in 2011 when a booby trap bomb exploded under his car and in 2010 Catholic police officer Peadar Heffron was seriously injured by a dissident republican bomb.
Jude Helliker, head of human resources at the PSNI, said: "The PSNI has commissioned an independent research project into how we recruit under-represented groups applying for a career in the PSNI.
"We are committed to ensuring that the composition of the Police Service of Northern Ireland is representative of the whole community. It is anticipated that the research will be completed in the autumn, and the findings will be presented to the Northern Ireland Policing Board in due course."
There have been warnings that the controversial 50/50 policy may have to be reintroduced in a bid to ensure the organisation is properly representative. The 50-50 rule operated from 2001 to 2011.
It was introduced as part of Patten and meant that half of all officers had to be Catholic. It was brought to an end in 2011 when the number of officers from a Catholic background rose from 8% to around 30%.
Policing expert, Dr Jonny Byrne of the Ulster University said: "Representation is key to confidence in policing. We must do everything in our power to make sure the PSNI is fully representative of all communities in Northern Ireland. 50/50 was a necessary requirement here for policing reform. We maybe need to revisit that conversation around the reintroduction of 50/50.
"There are a number of anecdotal reasons for the reluctance (of Catholics to join) such as the dissident threat against Catholic police officers and the legacy of the conflict. This study is an opportunity to look at what the stumbling blocks are and how to address them."
The findings from the research into recruitment barriers are due to presented to the Policing Board in October and any recommended changes will be made ahead.
Police figures show that Catholics are greatly under-represented at recruitment level, with just 30% of those applying during three recent recruitment drives from a nationalist/republican background. Figures also show that of 401 officers appointed from phase one of the recent recruitment campaign, 77 were Catholic, 319 Protestant and five undetermined. Between 20 and 25% of those to make it through to merit pools were Catholic.