It depends. Was the review your opinion ( what you think, based on your experience), or a false allegation?One is an opinion, which is not illegal. The other is libel, which is illegal. You can be sued for libel.For example, you order a vase through company A. You receive the vase and decide that you don’t like the color, so you ship it back to the company for a refund. The company clearly states that you need to pay return shipping, and you do. You receive your refund in a timely fashion.In that case, your review should give your opinion (I didn’t like the color), but also the facts (company A gave me a refund within their stated time frame). It isn’t the company’s fault that you didn’t like the color, and they handled your return correctly.If however, your review was dishonest, and you made things up or verbally attacked the company because you didn’t get your way and thought that a bad review would get them to do what you want, that is libel.For example, you received the vase in perfect condition, but decide that you don’t like the color. So you decide to return it, but you don’t want to pay for the return shipping (which is clearly posted on the company’s website), so you call Company A and lie, telling them that the vase arrived broken. Company A asks you to ship the broken vase back or send them a picture of the broken vase in the box with their shipping label shown in the picture. This is all clearly posted on their website in their refund policy. You have no proof of the broken vase, but the company has you on a recorded call. Instead of following their clearly posted policy, you post a negative review about the company something along the lines of “ Company A sent me a broken vase (no, they didn’t) and refused to give me a refund (a lie, they didn’t refuse to give a refund, they asked for proof that the vase was broken before they refunded you). They refused to work with me (another lie), and their customer service rep was rude and incompetent.In that case you posted a review filled with lies and inaccuracies, with no proof on your end, and plenty of proof on theirs.Bad reviews can have a very negative impact, they can cost a company money in the form of lost business, and employees can lose their jobs. If your review is libelous, then the company can sue you for lost business and wages, and win.In order to avoid being sued, first of all, try to resolve any problems through customer service as companies will work with you. Make sure you read and understand their description and policies thoroughly before you order. Ask questions if you don’t understand something.Second, make sure your review is factual and honest, if it is your opinion, clearly state that it is your opinion by saying words like “I didn’t like” or “In my opinion”. If it is factual, make sure you can back it up with evidence such as pictures or recorded conversation.Third, don’t try to bully someone into giving you what you want by threatening to write a bad review.