It’s hard to miss legal advertising on local television, where in some cases the ads are so prevalent that station traffic departments face the same sort of spacing issues that auto ads often bring. But a move by the Federal Trade Commission could put a damper on such advertising.

The FTC has fired off letters to several law firms expressing concerns that some of their television spots that solicit clients for personal-injury lawsuits against drug manufacturers may be considered deceptive or unfair under federal guidelines. The FTC’s warnings say the ads must have competent and reliable scientific evidence to substantiate the claims.