A study conducted by Lex Machina, a Menlo Park, California-based legal analysis company, lists Apple Inc. (AAPL) as number one among the top most sued companies on US patent- patent-infringement lawsuits.

Lex Machina scrutinised 6,092 patent-infringement suits filed and found that 13 per cent of the cases were filed against 10companies; three of these 10 companies filed more than 100 lawsuits.

"The patent litigation environment continues to be active and at times unpredictable ... There is still growth in patent litigation and clearly a measurable percentage of that growth comes from so-called patent monetization entities," Owen Byrd, general counsel for Lex Machina, told Bloomberg in an interview.

The study also found that companies usually decide to fight lawsuit instead of agreeing to a settlement because they have more chances of winning. Apparently, the number of patent-infringement lawsuits that were ruled out had been increasing since 2011.

On the other hand, respondents of a patent lawsuit had better chances of collecting damages. The study saw that the top ten damage awards in 2013 were cases involving companies that were directly competitors.

Some companies, however, are calling for lawmakers to come up with a law that would discourage patent owners to take advantage of the costly litigation process to demand for quick settlements.

Julie Samuels, executive director of Engine Advocacy, a San Francisco-based group, is calling for severe patent lawsuit law.

"When you're talking about hundreds of thousands of software patents sitting out there in the world, you need a very small percentage of them to cause real damage," she said.

Lex Machina lists Apple Inc as number one for having 59 cases against the company; Amazon at number 2 with 50 cases; AT&T at number 3 with 45 cases; Google at number 4 with 39 cases; Dell number 5 with 38 cases; HTC number 6 with 38 cases; Samsung at number 7 with 38 cases; Microsoft at number 8 with 35 cases; LG at number 9 for 34 cases; and finally HP with 34 cases.