The government is investigating whether pay-TV providers like Comcast, Time Warner Cable and AT&T are improperly restricting competing online video services with tactics like data caps. The Wall Street Journal reports that the Justice Department has spoken with video providers like Netflix and Hulu and several cable companies as part of the probe. Cablers say data-cap efforts are a way to deal with ever-increasing traffic on their expensively built-out networks, but opponents say they really are attempting to limit competition for the cable companies’ own channel offerings. The WSJ says one part of the probe is looking at Comcast’s Xfinity app: The company said in March that using the service would not count against subscribers’ data usage the same way Netflix or Hulu might be. If that’s found to be against antitrust rules, it could mean Comcast is in violation of its agreements that cleared the way for its acquisition of NBCUniversal. Also in play is cable companies’ TV Everywhere initiative, where online access requires a verified cable subscription, as well as the distribution contracts content providers sign with cable systems.