The latest lawsuit that could be a thorn in Google’s side is one between mobile device maker HTC and Apple (AAPL) over patents. Apple claims HTC is infringing on its iPhone patents (it has a similar suit going on with Samsung over similar issues). HTC is a key partner with Google and makes a great number of smartphones that use Google’s Android operating system.

Google CEO Eric Schmidt told ZDNet Asia that Google fully supports HTC in the suit, but he also said that he’s “not worried about this.”

“We have seen an explosion of Android devices entering the market and, because of our successes, competitors are responding with lawsuits as they cannot respond through innovations,” he said, according to a story from CNET. “I’m not too worried about this.”

The case Schmidt was referring to is a ruling against HTC by an administrative law judge for the U.S. International Trade Commission, finding that HTC has violated two Apple-owned patents. That could have some big effects on HTC going forward because the ITC has the power to limit companies from importing products that it finds violating patents.

More legal battles to come

There’s another ruling yet to come in that case by the ITC’s full panel of judges, and Google is backing HTC for that case. But if the panel rules against HTC, the company could find its smartphones banned from being imported from the U.S., and if Apple wins on these two key patents, it could also affect other smartphone manufacturers, as well – including those that make Android phones. Schmidt implied that Google would help HTC in the legal battle, but didn’t really specify how.

HTC and Apple’s patent fight is hardly the only one going on. Apple is battling Samsung over patents, while Microsoft (MSFT) is asking Samsung for a $15 royalty on every Android phone it sells because of other patents that company owns. Microsoft collects royalties from lots of other tech companies, including HTC. Apple and Research In Motion (RIMM), the maker of BlackBerry, recently lost a battle with Kodak over camera patents in mobile devices that could result in as much as $1 billion paid to the camera company. Google is also embroiled in a legal battle with Oracle regarding code used in the Android operating system that Oracle alleges infringes on patents it owns for code for the programming language Java.

So on the one hand, as Schmidt says, this is just another day in the smartphone business. Patent fights and lawsuits spring up all the time, with companies paying each other royalties on them most of the time. What makes the HTC issue give pause, though, is the fact that the products could be barred from U.S. shores if HTC and Google lose.

But Schmidt had an answer for that scenario, too: “We will make sure they don’t lose, then.”