Experience Tumblr Like Never Before
As a piece of advice to anyone who ever gets involved with clients from hell that attempt to stiff you on art work, design work, etc that I wish I had learned sooner instead of assuming that being too poor to afford copyright attorneys I know meant that I had to sit here and accept design theft...
...in the United States, you can take the aforementioned non-compliant client to small claims court, assuming it falls under that threshold. Different states have different thresholds for what constitutes a small claim, but overall, it should cover most artists on Tumblr. (I say this because even at my historic design rates and the extent of work I did, I manage to fall under Florida's $5000 threshold.)
Of course, I'm in this situation currently, so that's why I bring this up. Essentially, I wish someone told me that I didn't need an attorney while working as a lower-tier designer sooner.