A report that was recently leaked about an experiment in emotional manipulation carried out by Facebook in 2012 led to criticism and complaints. Facebook is now facing investigation by UK regulators and may even by slapped with a hefty fine.

The UK’s Information Commissioner’s Office enforces the Data Protection Act. It’s concerned that the experiment may have compromised the anonymity of UK citizens and infringed British law. If so, the regulator can demand a future policy change and fine the social-networking site up to $850,000 (£495,261)

Facebook’s week-long experiment tested the