Interesting concept. It is more often said that government influences laws! Influence can be variously defined (as per American Heritage Dictionary) as a power to affect a person or course of events; to sway opinion and action based upon power, wealth, prestige; to create an effect through imperceptible means; to modify and affect the development or condition of someone or something.
With this understanding, I'd be more apt to say laws constrain and/or direct government rather than influence government. But an instance of law influencing government might be when Federal Environmental law influenced then Governor Schwarzenegger to independently partner with Florida and the UK to institute more stringent environmental policy in California than exists at the Federal level.
In democratic countries, the laws really do influence the government. The government very rarely acts in ways that are clearly against the law. They may try to get around laws they don't like, but they cannot be seen to flagrantly break any laws. I think that in countries like the US, there is enough respect for the laws that government officials will generally not try to break the law (I'm talking here about in their official actions, not in personal actions).