Will I get into trouble if I post any old photo on Tumblr?

[KSV]

It seems people are posting photos they have found online all the time. What about copyright laws though?

How can I post any celebrity pictures on Tumblr then? I don't have the rights to these photos but I'd still like to post them.

I need some clarification.

[Amber]

You don't need credit or anything. Post all you want.

[bcnu]

It is technically a copyright infringement to publish and distribute copies of things for which YOU do not own the rights. Simple as that.

The fact that you see criminals doing illegal stuff doesn't make it legal for you to do exactly the same thing, even if you know you won't be caught. You could be the first, or MAYBE those others actually have obtained the necessary licenses and have no obligation to explain to you how that happened.

As a practical matter, only the copyright owners know for sure and if they don't care, why should anyone else?