In the United States, copyrighted material may be used without permission in limited ways subject to quite expansive criteria. There are four common tests of Fair Use.
As an example, I will use the photo of the musical group GrooveLily that I used in Christmas Presents without permission.
- What is the character of the use? Is the use personal, commentary or review, or is the use commercial - am I putting it on a t-shirt and selling it? I am using the photo to promote a musical group that I like.
- What is the nature of the work to be used? Is it fact or imaginative? You can copyright text of a news story but you can't copyright the facts in that story. You can't take someone else's fictional story and claim it as your own. The photo is a mix, it is an artistic work of real people.
- How much of the work is used? Am I using a sentence, a paragraph, the whole damn novel? The photo is used in its entirety. None of their music is reproduced without permission.
- What is the effect on the work's value? If my use of the work were seen by millions, what would be the effect? Would it diminish the value of the original work? This is a publicity photo. I linked back to the GrooveLily website. If millions saw it GrooveLily might sell many more CDs. I'm guessing they would like that.
So, to answer your questions. No, I didn't bother to get permission. Yes, I do know the copyright laws (probably damn well better than you do). I don't need permission because everything I use in all my posts is well within the concept of Fair Use.
In producing this work, I referenced without permission a publication by the University of Texas. It was Fair Use.