How to select a check box in selenium webdriver 2?

Here is the site i need to select check box in selenium webdriver. Code

<div class="login-form__checkbox">
  <div class="fblock active">
    <div class="focusbox">
      <span class="abs" style="width:0px; height:0px; overflow:hidden; font-size:0px; zoom:1;">
        <input id="checkbox_accept-terms" type="checkbox" name="register[rules]"/>
      </span>
      <label class="icon f_checkbox inlblk vtop selected" relname="register[rules]"               for="checkbox_accept-terms"/>
      <label class="selected" for="checkbox_accept-terms">
        <strong>Rules</strong>                                                                                                                                                              
      </label>
    </div>
  </div>
</div>

i trying

driver.findElement(By.id("checkbox_accept-terms")).click();

and

driver.findElement(By.xpath("//span[@id='checkbox_accept-terms']/div[3]/div/div/label[1]")).click();