I have a clothing line reflective of common slang phrases in different cities. I recently saw a phrase on a piece of clothing that I would like to use. I checked the USPTO website and its not listed. I plan to trademark the phrase...
Remember that not everything you use in commerce can be trademarked -- you can only acquire trademark protection on names, logos, phrases, etc., that "identify" your products or company. A phrase on a t-shirt is trademarkable, but only if that phrase causes people who read it to think about your company. The phrase "just do it" is trademarked, because when you read it, you associate the phrase with Nike. However, if Nike put out a line of shirts that said "Kiss my shiny metal butt" or something, that phrase would likely NOT be trademarkable by Nike, because people don't associate that particular phrase with Nike (or course, if Nike started using that logo in their ads and stuff so that it became their logo, that's another story...).
The point is, trademark law is not about staking a claim to something and then keeping others from using something -- it's about developing your company's identity, and protecting that.
Will the person who used it first be able to take any legal action against me?
Probably not, but there is a possibility. If the other party can claim common-law rights to a trademark, then they can use and protect their mark within their own geographical region. If you manage to obtain a federal registration for your mark, you will be able to exclude others from using the mark, except for "senior" users that use the mark in their own geographical, such as this person, and any senior user may exclude you from using the mark in their own geographical region. A registered mark holder cannot keep a senior user from using the mark in their own geographical area, but can keep the senior user from expanding the use of their mark to other areas.
Can I limit or stop their use of the phrase?
Is this the best way of going about ensuring I can use it as well?
As I noted above, unless you are planning on using this phrase as your corporate phrase or identity, then it will be difficult to obtain trademark protection on the logo. If you are planning on using it for that purpose, then a registered trademark, if you can get one (not everything is trademarkable), is the best way to go.
If the phrase is not going to be used as your "logo," or if the phrase isnot otherwise trademarkeable, then just use the phrase.