You've heard it said that we are no longer under the Law, meaning the Law given to Moses by God on Horeb. But the Law which God requires of all mankind is the Law of Righteousness. Therefore, St. Paul says that those who do what is in the Law (of Moses) fulfilling the requirements of righteousness (which is the Law which Abraham was under. Namely, to walk before the Lord perfectly), without being under the Law are a law unto themselves. Wicked and deceived people go around trying as they may to conflate the Mosaic Law and the Law of Righteousness which was given through Christ, so that by having been excused by God from the Law they might excuse themselves from righteousness. These people are lawless, and they never stop making excuses for their wickedness. They live without the natural restraint which comes from living righteously. They reject righteousness for what they call liberty, when it is liberty which is given by Christ to His people so that they can be righteous. This is the lawlessness I was speaking of.
"Every art and every inquiry, and similarly every action and choice, is thought to aim at some good; and for this reason the good has rightly been declared to be that at which all things aim." ~Aristotle~