If I'm given resources by a client, should I look up the licenses of each one of those resources?
Can this affect me in any way legally?
No. You should have written in your contract that client has all rights to materials he gives to you. With your invoice you should give him list (names) of files you bought to use for the project and the ones he gave you.
Sometimes I print dummy layout with signature so I will know which file is which.
I keep them for anyone trying to ask for license or extortion.
I, personally, don't concern myself immediately with client provided assets. As @Szczerzo answered, the contract should state that you are not responsible for rights to client-provided resources as well as a clause stating the client is responsible for any and all legal fees or damages resulting from their supply of unlicensed assets. And there should be a record of the assets and how they were provided.. an email.. a link... something. To show that they were indeed provided to me not sourced by me.
However, if a client sends me something which I clearly know they do not own, that's a different matter. I will ask them if they have rights, via email so it's written. If they reply with a "yes" then there's no reason for me to disbelieve them. And I have a written record of the client stating they had rights to use the asset. If the client lied to me.... well I can't be held responsible if I'm lied to. I've done my due diligence by specifically asking about it. It's unreasonable to expect a designer to perform a rights search like an attorney would. And it's not feasible from a workflow standpoint to have to track down the rights of everything every client provides. You sort of have to take their word for it.
If the client indicates they "found" the resource or otherwise do not have the rights to it, I make suggestions for alternatives. If they argue about the use, I get more protective over the asset and will eventually outright refuse to use it to avoid undue liability on my part. Often explaining that I, myself, and creating digital assets for them and infringing upon the rights of other digital assets is poor practice if they expect their rights to be honored by others.
As others have pointed out, there should be clauses in your contract that stipulate that the client acknowledges that they have full rights to use the assets and that they will defend you against any such damages should a dispute arise. To take these answers a bit further, I'll add the clauses from our boilerplate web design and development contract.
Client warrants that: (a) it has all authorization(s) necessary for hypertext links to third party Web sites; and; and (b) that the Client Content does not infringe or violate any right of any third party. Client shall provide all necessary Client Content, including database files, reports and other materials for implementation of the TourismBuilder application.
.. and just in case there is infringement:
Indemnification by Client
Client agrees to indemnify, defend, and hold harmless TourismBuilder, its directors, officers, employees, agents, and vendors, and defend any action brought against same with respect to any claim, demand, cause of action, debt or liability, including reasonable attorneys' fees, to the extent that such action is based upon a claim that:
(i) would constitute a breach of any of Client's warranties, hereunder; (ii) arises out of the negligence or willful misconduct of Client; or (iii) any of the Client Content to be provided by Client hereunder or other material on the Site provided by Client infringes or violates any rights of third parties, including, without limitation, rights of publicity, rights of privacy, patents, copyrights, trademarks, trade secrets and/or licenses.
We just finished a project that had over 200,000 images alone, not to mention 1000s of articles. Even in a large company, checking on the behalf of the client that he/she has to right to incorporate the assets would take twice as long as completing the project itself - it's just not possible. And, that's the reasons for clauses like this. It's the clients responsibility to give you assets he/she has full rights to use; and, per clauses like these, the client agrees to protect you against such claims, including reimbursing you for any financial expenses that would be incurred because of such claims (legal expenses).
These are pretty standard. They have been well vetted by our attorneys and used in thousands of projects. I wouldn't copy and paste these verbatim into your contract, but you could get pretty close. Show them to your lawyer and have incorporate something similar and you will no longer have to worry about your liability when it comes to the assets someone else is giving to you. (iii) most explicitly deals with your question. So should you investigate the licenses of each asset your client gives you? No, not at all. As far as your liability goes, if you willingly participate in using material you or you and your client both know to infringe copyrights, then yes, you would be as equally liable as the client in those violations.