The US Department of Justice, the Environmental Protection Agency, and attorneys general in at least 29 states are already investigating VW, and politicians are pushing for criminal and civil actions against the company. According to Reuters, there could be several legal routes available, too. One option is to bring tax fraud charges, and that would require proving the automaker knew it was making untrue claims about the diesel models.
There's also the option of bringing a case under the False Claims Act, which prohibits fraud against the government. According to Reuters, a maximum penalty under the law would be three times the tax credit and another $5,000 for each vehicle that received it.
The company is also facing a class-action lawsuit from disgruntled owners. To aid its defense against all of these claims, VW has hired the same firm that worked with BP during the Deepwater Horizon oil spill. Outside of the US, prosecutors in Germany have just started to build a case against former CEO Martin Winterkorn for alleged fraud.
In addition to these potential legal penalties, VW could be fined around $18 billion by the EPA for the emissions infractions. The agency's investigation is getting the added backing of its Canadian counterpart. Although, the actual settlement is expected to be far less.