Facebook Inc. attorneys had just one weekend to conduct due diligence ahead of the more than $2 billion acquisition of virtual reality developer Oculus VR, Facebook CEO Mark Zuckerberg recently testified in a Dallas federal courtroom. According to M&A lawyers, a short timeframe like this is sometimes backed by sound business sense, though there are precautions in-house lawyers can take to protect the company when conducting such a quick review.

Video game maker ZeniMax Media Inc. sued Oculus for copyright infringement and misappropriation of trade secrets, among other allegations, in U.S. District Court for the Northern District of Texas in 2014, adding Facebook as a defendant after it purchased the company. In the complaint, ZeniMax alleged that Oculus’ chief technology officer, John Carmack, stole ZeniMax’s intellectual property when he left the company in 2013 and that Facebook knew this when it closed the deal with Oculus.